Which is true? A real emf device has internal resistance and an ideal emf device does not. An ideal emf device has internal resistance and a real emf device does not. A real emf device sets up a potential difference and an ideal emf device does not. An ideal emf device sets up a potential difference and a real emf device does not.
A junction point in the wire of a circuit has inward current of 5.0 A. Which is true? The outward current can be more than 5.0 A. The outward current must be 5.0 A. The outward current can be less than 5.0 A.
Which is correct about an ammeter? The internal resistance must be much smaller than the other resistances in the circuit. The internal resistance must be much greater than the other resistances in the circuit. The internal resistance must be comparable to the other resistances in the circuit.
When an initially uncharged capacitor is charged in an RC circuit, what happens to the current in the circuit? It is initially 0 and then increases exponentially with time. It is initially at its maximum value and then decreases exponentially with time. It is initially 0 and then increases linearly with time. It is constant during the charging. It is initially at its maximum value and then decreases linearly with time.
When an initially uncharged capacitor is charged in an RC circuit, what happens to the potential difference across the resistor? It is initially 0 and then increases exponentially with time. It is initially 0 and then increases linearly with time. It is constant during the charging. It is initially at its maximum value and then decreases exponentially with time. It is initially at its maximum value and then decreases linearly with time.
If we monitor a point on a wire where there is a current for a certain time interval, which gives the charge that moves through the point in that interval? the ratio of the time interval to the current the product of the current and the time interval the ratio of the current to the time interval
When the current density in a wire is uniform, which gives the amount of current through a cross section of the wire? the product of the cross-sectional area and the current density the ratio of the cross-sectional area to the current density the ratio of the current density to the cross-sectional area
Which is true? Resistance is the ratio of the current to the potential difference. Resistance is the ratio of the potential difference to the current. Resistance is the product of the potential difference and the current.
In a plot of current versus potential difference, which feature characterizes a device that obeys Ohm's law? The plot is symmetric about the vertical axis. The slope is zero. The plot is curved, with a constant positive curvature. The plot is curved, with a constant negative curvature. The slope is constant.
Which is true? The equation P = iV applies to any electrical energy transfer, but P = i2R applies only to dissipation. Both P = i2R and P = iV apply to dissipation. The equation P = i2R applies to any electrical energy transfer, but P = iV applies only to dissipation.
A 6 kg block is lowered down an incline with an angle of 46 degrees, and a distance of 7 m from point A to point B. A horizontal force F = 10 N is applied to the block between and as shown in the figure. The kinetic energy of the block at A is 16 J and at B, it is 26 J. How much work is done on the block by the force of friction between A and B?
A girl operates a radio-controlled model car in a vacant parking lot. The girl's position is at the origin of the xy coordinate axes, and the surface of the parking lot lies in the x−y plane. The motion of the car is defined by the position vector r = (2 + 2t2)i + (6 + t3)j, where r and t are expressed in meters and seconds, respectively. Determine the distance the car traveled in the interval from t = 0 to t = 3.6 s. The distance the car traveled in the interval from t = 0 to t = 3.6 s is m. Required information NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part.
There are two forces on the 1.49 kg box in the overhead view of the figure but only one is shown. For F1 = 16.8 N, a = 10.5 m/s2, and θ = 23.1∘, find the second force (a) in unit-vector notation and as (b) a magnitude and (c) a direction. (State the direction as a negative angle measured from the +x direction.)
A cannon is fired with an initial velocity of 120 m/s at an angle of 25° above a level field. The cannonball strikes the tallest tower of the castle, 3.4 s after it is fired. Δx At approximately what height above the ground does the cannonball strike the tower? NOTE: this diagram is NOT to scale! 50.7 m 131 m 116 m 343 m 191 m
Two arrows are shot vertically upward. The second arrow is shot after the first one, but while the first is still on its way up. The initial speeds are such that both arrows reach their maximum heights at the same instant, although these heights are different. Suppose that the initial speed of the first arrow is 31.3 m/s and that the second arrow is fired 1.74 s after the first. Determine the initial speed of the second arrow. Number Units
A student of mass 63.4 kg, starting at rest, slides down a slide 18.2 m long, tilted at an angle of 30.1∘ with respect to the horizontal. If the coefficient of kinetic friction between the student and the slide is 0.113, find the force of kinetic friction, the acceleration, and the speed she is traveling when she reaches the bottom of the slide. (Enter the magnitudes.) (a) the force of kinetic friction (in N) N (b) the acceleration (in m/s2) m/s2 (c) the speed she is traveling (in m/s) m/s
A worker kicks a flat rock lying on a roof. The rock slides up the incline 10.0 m to the apex of the roof, and flies off the roof as a projectile. What maximum height (in m) does the rock attain? Assume air resistance is negligible, vi = 15.0 m/s, μk = 0.430, and that the roof makes an angle of θ = 40.0∘ with the horizontal. (Assume the worker is standing at y = 0 when the rock is kicked.) m
A 100-g projectile traveling at 750 m/s strikes and becomes embedded in the 50−kg block, which is initially stationary. Compute the kinetic energy lost during the impact.
An electron is a subatomic particle (m = 9.11×10−31 kg) that is subject to electric forces. An electron moving in the +x direction accelerates from an initial velocity of +8.83×105 m/s to a final velocity of 1.19×106 m/s while traveling a distance of 0.00693 m. The electron's acceleration is due to two electric forces parallel to the x axis: F1→ = 7.06×10−17 N, and F2→, which points in the −x direction. Find the magnitudes of (a) the net force acting on the electron and (b) the electric force F2→. (a) Number Units (b) Number Units
A block of mass m = 3.2 kg is released from rest at point A (see Figure beiow) slides down a rough surface that is one quarter of a circle of Radius R = 3.6 m. If the block speed at point B is VB = 3.0 m/s, how much work is done on the block by friction as it slides down from point A to B. Select one: a. 62.50 J b. -26.501 C. +98, 50 J d. 127.30 J
Two balls, ball A and B, are rolled on the ground with the velocity of 10 m/s and 15 m/s, respectively, as shown in Figure 3. Calculate the magnitude and the direction of the velocity of ball B relative to ball A. Figure 3
The plane shown in the figure is taking an aerial photograph with a camera lens that has an angular coverage of 70∘. The ground below is inclined at 5∘. If the angle of elevation of the plane at B is 50∘ and distance BC is 3500 feet, estimate the ground distance AB (to the nearest foot) that will appear in the picture.
In the figure, a climber leans out against a vertical ice wall that has negligible friction. Distance a is 0.885 m and distance L is 2.00 m. His center of mass is distance d = 0.86 m from the feet-ground contact point. If he is on the verge of sliding, what is the coefficient of static friction between feet and ground? μs = Number Units
A 1.2-kg mass is projected down a rough circular track (radius = 2.0 m) as shown. The speed of the mass at point A is 3.2 m/s, and at point B, it is 6.0 m/s. How much work is done on the mass between A and B by the force of friction? −8.9 J −7.3 J −8.1 J −6.6 J . 24 J
A 120 kg box is pulled by the forces shown in FIGURE Q1. The kinetic friction, μk between the box and the surface is 0.3 and it moves from a resting position. FIGURE Q1 a. Construct the free-body diagram and kinetic diagram for the box. [4 marks] b. Determine the required distance for the box to attain a speed of 9 m/s, using the principle of work and energy. [8 marks] c. Given that the horizontal surface is smooth, determine the required distance for the box to attain a speed of 14 m/s using the principle of work and energy, and explain the changes in part (b). [8 marks]
In the figure, a horizontal scaffold, of length 2.86 m and uniform mass 52.6 kg, is suspended from a building by two cables. The scaffold has dozens of paint cans stacked on it at various points. The total mass of the paint cans in 74.8 kg. The tension in the cable at the right is 798 N. How far horizontally from that cable is the center of mass of the system of paint cans?
A 16.0-kg cannonball is fired from a cannon with muzzle speed of 900 m/s at an angle of 32.0∘ with the horizontal. A second ball is fired with the same initial speed at an angle of 90.0∘. Let y = 0 at the cannon. (a) Use the isolated system model to find the maximum height reached by each ball. hfirst ball = mhsecond ball = m (b) Use the isolated system model to find the total mechanical energy of the ball-Earth system at the maximum height for each ball. Efirst ball Esecond ball = J
Suppose the electric field between the electric plates in the mass spectrometer of Fig. 20−38 is 2.04×104 V/m and the magnetic fields B = B′ = 0.40 T. The source contains carbon isotopes of mass numbers 12, 13 , and 14 from a long-dead piece of a tree. (To estimate atomic masses, multiply by 1.67×10−27 kg. ) Figure 20−38 (a) How far apart are the lines formed by the singly charged ions of each type on the photographic film? mm (b) What if the ions were doubly charged? mm
A 102 g wooden block is initially at rest on a rough horizontal surface when a 11.4 g bullet is fired horizontally into (but does not go through) it. After the impact, the block-bullet combination slides 6.5 m before coming to rest. If the coefficient of kinetic friction between block and surface is 0.750, determine the speed of the bullet (in m/s) immediately before impact. m/s
A 197-g block is pressed against a spring of force constant 1.62 kN/m until the block compresses the spring 10.0 cm. The spring rests at the bottom of a ramp inclined at 60.0∘ to the horizontal. Using energy considerations, determine how far up the incline the block moves from its initial position before it stops under the following conditions. (a) if the ramp exerts no friction force on the block (b) if the coefficient of kinetic friction is 0.460
An outfielder throws a baseball to his catcher in an attempt to throw out a runner at home plate. The ball bounces once before reaching the catcher. Assume the angle at which the bounced ball leaves the ground is the same as the angle at which the outfielder threw it as shown in the figure, but that the ball's speed after the bounce is onehalf of what it was before the bounce. (a) Assuming the ball is always thrown with the same initial speed, at what angle θ should the fielder throw the ball to make it go the same distance D with one bounce (blue path) as a ball thrown upward at 40.0∘ with no bounce (green path)? (b) Determine the ratio of the time interval for the one-bounce throw to the flight time for the no-bounce throw. tone-bounce tno-bounce =
9 A 6 kg mass is projected up a rough circular track (radius = 0.43 m, diameter = 0.86 m) as shown. The speed of the mass at point A is 9.55 m/s. What is the velocity of the mass at point B if friction does work W = −11.75 N? A. 70.49 m/s B. 9.31 m/s C. 2.42 m/s D. 8.4 m/s E. 5.94 m/s
A horizontal rifle is fired at a bull's-eye. The muzzle speed of the bullet is 700 m/s. The gun is pointed directly at the center of the bull's-eye, but the bullet strikes the target 0.024 m below the center. What is the horizontal distance between the end of the rifle and the bull's-eye? Number Units
In the figure, a horizontal scaffold, of length 2.81 m and uniform mass 44.4 kg, is suspended from a building by two cables. The scaffold has dozens of paint cans stacked on it at various points. The total mass of the paint cans in 73.1 kg. The tension in the cable at the right is 748 N. How far horizontally from that cable is the center of mass of the system of paint cans? Number Units
A pendulum bob with a mass of 0.26 kg is attached to a 1.5 m long string as shown. As the pendulum bob swings from point A, where the angle θ = 37∘, to point B at the bottom of its arc, determine the change in the gravitational potential energy of the pendulum bob-earth system.
A projectile is fired with an initial speed of 150 m/s and angle of elevation 60∘. The projectile is fired from a position 100 m above the ground. (Use g = 9.8 m/s2. Round your answers to the nearest whole number.) (a) Find the range (in m ) of the projectile. m (b) Find the maximum height (in m) reached. m (c) Find the speed (in m/s) at impact. m/s
A 1.2-kg mass is projected down a rough circular track (radius = 2.0 m ) as shown. The speed of the mass at point A is 3.2 m/s, and at point B, it is 6.0 m/s. How much work is done on the mass between A and B by the force of friction? −8.9 J −7.3 J −8.1 J −6.6 J −24 J
A champion athlete can produce one horsepower (746 W) for a short period of time. If a 70−kg athlete were to bicycle from the bottom to the top of a 295-m high mountain while expending power at the rate of 566 Watts, she would take at least how many seconds to reach the top.
The satellite in form of solid cylinder of radius 2.3 m and mass 1857.1 kg should rotate at the constant rate. For this four rockets each of mass 114.3 are placed as shown in the figure. What is the steady force required from each rocket if the satellite should reach 0.9 rps in 2.4 seconds.
This figure shows a sinusoidal wave that is traveling from left to right, in the +x-direction. Assume that it is described by a frequency of 28.8 cycles per second, or hertz (Hz). (a) What is the wave's amplitude (in cm )? (b) What is the wavelength (in cm )? cm (c) Calculate the wave's period (in s). (d) Compute the speed of this wave (in m/s ). m/s
Two 8.8 kg bodies, A and B, collide. The velocities before the collision are v→A = (30i^ + 26j^) m/s and v→B = (−22i^ + 14j^) m/s. After the collision, v→A′ = (−13i^ + 18j^) m/s. What are (a) the x-component and (b) the y-component of the final velocity of B? (c) What is the change in the total kinetic energy (including sign)? (a) Number Units (b) Number Units (c) Number Units
Fred (m = 84 kg) & Barney (m = 78 kg) are trying to lower a baby woolly mammoth (m = 330 kg) down a cliff using a frictionless pulley. They are 16.0 meters from the edge of the cliff. Unfortunately, the mammoth is too heavy and Fred and Barney are being dragged along the ground at top of the cliff. If the coefficient of friction between Fred and the ground is 0.24, and between Barney and the ground is 0.26 , what is the acceleration of the mammoth (in units of m/s^2) in the j^ direction? Provide your answer as a positive or negative number ONLY, with 2 decimal places (e. g. 1.25 or -1.25). Do not write the units (e. g. s or m or m/s etc.) in the answer box. Do not use scientific notation.
Two regions of a mass spectrometer are shown below. In the velocity selector region, the ions are focused into a beam with a single speed in the direction shown using an electric field of 500 V/m and magnetic field |B→1| = 0.5 T perpendicular to one another. In the region to the right, a single magnetic field, B→2 is used to deflect the particles in a circular path which land at the detector. In this region, electrons experience a force of 1.0×10−16 N and move in the circular path shown. What is the strength and direction of the magnetic field, B→2? Ignore gravity. 0.63 T out of the page 1.6 T out of the page 0.63 T into the page 630000 T out of the page 1.6 T into the page
An object is sent into a projectile (parabolic motion) from h = 1.35 m above ground level with an initial velocity of v0 = 2.5 m/s and at an angle of θ = +28∘. a) Find the total time (from A → B → C) to reach the ground level? (4 points) b) Find the maximum height object can reach from ground level (Y displacement from A→B)? (3 points) c) Find Y velocity component of the object at point C? (3 points)
A uniform solid disk is mounted on an axle in such a way that it is free to rotate about a horizontal axis. The radius of the disk is 0.450 m and its mass is 30.5 kg. As shown in the diagram, two forces F1 = 89.5 N and F2 = 135 N applied to the disk sets the disk rotating with a constant angular acceleration. Assume the axle is frictionless. (a) Calculate the magnitude and direction of the net torque produced by the two forces. magnitude N⋅m direction (b) Determine the magnitude of the angular acceleration of the disk. rad/s2
A block of mass m = 8.30 kg slides down from an inclined frictionless ramp that forms an angle θ = 26.50∘ with the ground. A long spring with a relaxed length s0 = 1.99 m and a spring constant k = 537.98 N/m is situated at the base of the ramp. The block started at a distance d = 3.06 m from the tip of the relaxed spring, with initial velocity of v = 9.42 m/s. What is the length of the spring when the block compresses the spring and temporarily comes to a rest on the ramp? Round your answer to 2 decimal places.
A student of weight 670 N rides a steadily rotating Ferris wheel (the student sits upright). At the highest point, the magnitude of the normal force F→N on the student from the seat is 584 N. (a) What is the magnitude of F→N at the lowest point? If the wheel's speed is doubled, what is the magnitude FN at the (b) highest and (c) lowest point? (a) Number Units (b) Number Units (c) Number Units
A series circuit has two resistors with values R1 = 3.00 Ω and R2 = 0.250 Ω. If the potential of the circuit is 5.00 V, what is the current through R1? 21.7 A 1.54 A 1.67 A 20.0 A
A current of 1.0 A from a 1.0 mm diameter wire enters a sphere which is 1.0 m in radius. The current then exits through a 1.0 mm diameter wire on the opposite side of the sphere. What is the smallest value of current density in the sphere? 1/π A/m2 1/(4π) A/m2 1/(2π) A/m2 1/(16π) A/m2
A circuit includes a capacitor that charges over time. If the resistance of the circuit is 3.0 Ω, the capacitance is 2.2 F, and the potential of the circuit is 5.0 V, what is the charge on the capacitor after a time of 10.0 seconds, assuming the capacitor is initially uncharged? 8.6 C 1.5 C 11 C 2.4 C
What is the initial charge on a capacitor with a capacitance of C = 0.500 F and an initial potential across the capacitor of V0 = 5.00 V? q0 = C
A beam of protons travelling at 1.00×105 m/s has a current density of 1.00 mA/m2. What is the density of protons in the beam? 2.46×104 m−3 3.28×108 cm−3 6.25×1010 m−3 7.25×1012 m−3
Which type of conductor would have the longest mean free time between collisions for conduction electrons? A conductor with small conductivity would have the longest time between collisions. A conductor with small resistivity would have the longest time between collisions. A conductor with large resistivity would have the longest time between collisions. All conductors have the same mean free time between collisions for conduction electrons.
A series circuit has two resistors with values R1 = 3.0 Ω and R2 = 0.25 Ω. If the current exiting the battery is 0.50 A, what is the potential difference across R1 ? 0.17 volts 0.12 volts 1.5 volts 1.8 volts
Aluminum has a resistivity of 2.75×10−8 Ω-m and a density of conduction electrons of 1.80×1029 m−3. Calculate the mean free time between electron collisions in aluminum and express the answer in units of 10−15 s. x10−15 s
A circuit includes a capacitor that charges over time. If the resistance of the circuit is 5.0 Ω, the capacitance is 0.20 F, and the potential of the circuit is 6.0 V, what is the potential across the capacitor after a time of 2.0 seconds, assuming the capacitor is initially uncharged? 2.0 V 5.2 V 4.0 V 0.81 V
A current of 1.00 A flows in an aluminum bar which is 10.0 cm long and 1.00 cm square sides. If electrons drift through the bar at a speed of 3.50×10−7 m/s, how many free conduction electrons are in the bar at any moment? 3.31×1022 7.00×1029 1.78×1024 1.79×1029
What is the magnitude of the electric field that must exist inside a 2.00 cm long, 220 Ω resistor if 1.00 A of current flows through it? kV/m.
A circuit includes a capacitor that charges over time. What is the time constant of the capacitor if the capacitance is 0.50 F and the resistance is 5.0 Ω ? 0.10 s 10 s 5.5 s 2.5 s
An example of non-ohmic resistance is carbon resistance. tungsten wire. diode. copper wire.
What is the current in a wire of radius R = 3.17 mm if the magnitude of the current density is given by (a) Ja = J0r/R and (b) Jb = J0(1 − r/R) in which r is the radial distance and J0 = 7.27×104 A/m2 ? (c) Which function maximizes the current density near the wire's surface? (a) Number Units (b) Number Units (c)
Uniform displacement-current density. The figure shows a circular region of radius R = 2.50 cm in which a uniform displacement current id = 0.650 A is out of the page. What is the magnitude of the magnetic field due to the displacement current at radial distances (a) 1.50 cm and (b) 5.60 cm? (a) Number Units (b) Number Units
Consider a point charge q = 1.1 μC, point A at distance d1 = 2.8 m from q, and point B at distance d2 = 0.95 m. (a) If A and B are diametrically opposite each other, as in Figure (a), what is the electric potential difference VA − VB? (b) What is that electric potential difference if A and B are located as in Figure (b)? (a) (b) (a) Number Units (b) Number Units
Three point charges are fixed in place in a right triangle, as shown in the figure. where y = 8.20 cm and z = 9.80 cm. Problem 16.022 - 2 - Direction of the net force on the +1.00−μC charge What angle does the force make with the −x-axis? A positive angle is counterclockwise from the −x-axis.
Example 23.5 Electric Field due to Two Charges Problem A charge q1 = 3.3 μC is located at the origin and a second charge q2 = −3.0 μC is located at the x axis, 0.30 m from the origin (Figure 23.14). Find the electric field at the point P, which has coordinates (0, 0.40)m. Figure 23.14 The total electric field E at P equals the vector sum E1 + E2, where E1 is the field due to the positive charge q1 and E2 is the negative charge q2
The charge configuration shown was created by performing 60.66 mJ of work to bring charges Q and q from an infinite separation to a separation of 3.64 m. Both charges are positive, and their sum is 10.73 μC, but their individual values are initially unknown. Let Q have the greater charge, i. e. Q > q. Part (a) How much charge, in microcoulombs, is on the charge with the greater amount? Q = μC Part (b) How much charge, in microcoulombs, is on the charge with the lesser amount?
A mass has a charge of q = 2e, where e is the charge on an electron. (a) Determine the electric potential (in V) due to the charge at a distance r = 0.260 cm from the charge. V (b) Determine the electric potential difference (in V) between a point that is 2 r away and this point, that is V(2r)−V(r). V (c) Determine the electric potential difference (in V) between a point that is r/2 away and this point, that is V(r/2) − V(r). V (d) How would the answers change if the electrons are replaced by protons? The sign of answer (a) would change. The sign of answer (b) would change. The sign of answer (c) would change. The sign of all answers would change. All answers would remain the same.
Charge q1 = 5.99⋅10−8 C is placed at the origin. Charges q2 = −2.01⋅10−8 C and q3 = 1.79⋅10−8 C are placed at points (0.125 m, 0 m) and (0 m, 0.219 m), respectively, as shown in the figure. a) Determine the magnitude of the net electrostatic force on charge q3. (You may enter your calculation using scientific notation.) N b) Determine the direction of the net electrostatic force on charge q3. (Enter the angle with respect to the positive x-axis). deg
A charge of +1 nC (1×10−9 C) and a dipole with charges +q and −q separated by 0.3 mm contribute a net field at location A that is zero, as shown in the figure below. (Assume r1 = 68 cm and r2 = 47 cm.) (a) Which end of the dipole is positively charged? (b) How large is the charge q? (Enter the absolute value.) q = nC
Let 13.0 eV electrons approach a potential barrier of height 6.0 eV. (a) For what minimum barrier thickness (in nm) is there no reflection? nm (b) For what minimum barrier thickness (in nm) is the reflection a maximum? nm
A quarterback is standing on the football field preparing to throw a pass. His receiver is standing 23 yd down the field and 15 yd to the quarterback's left. The quarterback throws the ball at a velocity of 43 mph toward the receiver at an upward angle of 32∘. Assume the quarterback is standing at the origin, the positive x-axis is down the field, and the positive y-axis is to the quarterback's left. Write the initial velocity vector v of the ball in component form (measured in mph). Round components to 1 decimal place. v =
A circular conducting loop with radius 2.10 cm is placed in a uniform magnetic field of 0.850 T with the plane of the coil perpendicular to the magnetic field as shown. The magnetic field decreases to 0.250 T in a time interval of 30.0 ms. What is the average induced emf in the loop during this interval? mV
(a) What is the average useful power output (in W) of a person who does 6.80×106 J of useful work in 7.60 h? W (b) Working at this rate, how long (in s) will it take this person to lift 2300 kg of bricks 1.40 m to a platform? (Work done to lift his body can be omitted because it is not considered useful output here.) s