A small 1000−kg SUV has a wheel base of 3.0 m. If 60% if its weight rests on the front wheels, how far behind the front wheels is the wagon's center of mass? 2.0 m 1.5 m 2.4 m 1.2 m
When opening a door, you push on it perpendicularly with a force of 55.0 N at a distance of 0.850 m from the hinges. What torque are you exerting relative to the hinges? 50.2 Nm 65.0 Nm 46.8 Nm 38.6 Nm
When tightening a bolt, you push perpendicularly on a wrench with a force of 165 N at a distance of 0.140 m from the center of the bolt. How much torque are you exerting relative to the center of the bolt? 46.2 Nm 23.1 Nm 30.5 Nm 62.5 Nm
A uniform plank rests on a level surface as shown below. The plank has a mass of 30 kg and is 6.0 m long. How much mass can be placed at its right end before it tips? (Hint: When the board is about to tip over, it makes contact with the surface only along the edge that becomes a momentary axis of rotation.) 10 kg 20 kg 40 kg 30 kg
The uniform seesaw shown below is balanced on a fulcrum located 3.0 m from the left end. The smaller boy on the right has a mass of 40 kg and the bigger boy on the left has a mass 80 kg. What is the mass of the board? 40 kg 10 kg 80 kg 30 kg
A uniform 40.0−kg scaffold of length 6.0 m is supported by two light cables, as shown below. An 80.0-kg painter stands 1.0 m from the left end of the scaffold, and his painting equipment is 1.5 m from the right end. If the tension in the left cable is twice that in the right cable, find the tensions in the cables and the mass of the equipment. Right cable 444.3N, left cable 888.5N, mass of equipment 16.0 kg Right cable 222.3N, left cable 333.5N, mass of equipment 8.0 kg Right cable 666.3N, left cable 333.5N, mass of equipment 32.0 kg Right cable 333.3N, left cable 222.5N, mass of equipment 10.0 kg
A farmer making grape juice fills a glass bottle to the brim and caps it tightly. The juice expands more than the glass when it warms up, in such a way that the volume increases by 0.2%. Calculate the force exerted by the juice per square centimeter if its bulk modulus is 1.8×10 9 N/m2, assuming the bottle does not break. 6.0 C 10^2 N/cm^2 8.0 C 10^2 N/cm^2 10.0 C 10^2 N/cm^2 4.0 C 10^2 N/cm^2
TV broadcast antennas are the tallest artificial structures on Earth. In 1987, a 72.0-kg physicist placed himself and 400 kg of equipment at the top of a 610-m-high antenna to perform gravity experiments. By how much was the antenna compressed, if we consider it to be equivalent to a steel cylinder 0.150 m in radius? Young's Modulus for steel is 20.0 × 10 10 Pa 0.400 mm 0.200 mm 0.100 mm 0.500 mm
The "lead" in pencils is a graphite composition with a Young's modulus of approximately 1.0×10 9 N/m2. Calculate the change in length of the lead in an automatic pencil if you tap it straight into the pencil with a force of 4.0 N. The lead is 0.50 mm in diameter and 60 mm long. 2.6 mm 0.8 mm 1.2 mm 2.4 mm
A uniform rope of cross-sectional area 0.50 cm2 breaks when the tensile stress in it reaches 6.00×10 6 N/m2. What is the maximum load that can be lifted slowly at a constant speed by the rope? 150 N 200 N 400 N 300 N
Two children push on opposite sides of a door during play. Both push horizontally and perpendicular to the door. One child pushes with a force of 17.5 N at a distance of 0.600 m from the hinges, and the second child pushes at a distance of 0.450 m. What force must the second child exert to keep the door from moving? Assume friction is negligible. 35.0 N 18.5 N 23.3 N 46.6 N
By how much does a 65.0-kg mountain climber stretch her 0.800-cm diameter nylon rope when she hangs 35.0 m below a rock outcropping? (For nylon, Y = 1.35×10 9 Pa.) 32.9 cm 35.0 cm 25.0 cm 40.5 cm
What is the maximum load that can be lifted by the rope with an acceleration of 4.00 m/s2? 200 N 213 N 105 N 113 N A uniform rope of cross-sectional area 0.50 cm2 breaks when the tensile stress in it reaches 6.00×10 6 N/m2.
An alpha-particle (m = 6.64×10 −27 kg, q = 3.2×10 −19 C) travels in a circular path of radius 25 cm in a uniform magnetic field of magnitude 1.5 T. What is the speed of the particle? 1.8 × 10^7 m/s 4.8 × 10^7 m/s 2.8 × 10^7 m/s 3.8 × 10^7 m/s
A cosmic ray proton moving toward Earth at 5.00 × 10 7 m/s experiences a magnetic force of 1.70 × 10 −16 N . What is the strength of the magnetic field if there is a 45∘ angle between it and the proton's velocity? Positive charge of a proton is 1.6 × 10 −19 C 3.55 × 10^−5 T 3.01 × 10^−5 T 4.55 × 10^−5 T 5.20 × 10^−5 T
A cosmic-ray electron moves at 7.5 × 10 6 m/s perpendicular to Earth's magnetic field at an altitude where the field strength is 1.0 × 10 −5 T. What is the radius of the circular path the electron follows? Negative charge of an electron = 1.6 × 10^−19 C Mass of an electron = 9.1 × 10^−31 kg 4.35 m 3.45 m 6.50 m 7.50 m
What voltage will accelerate electrons to a speed of 6.00 × 10−7 m/s? 6.00 × 10 −7 m/s? Negative charge of an electron = 1.6 × 10^−19 C Mass of an electron = 9.1 × 10^−31 kg 2.02 × 10^−24 V 4.02 × 10^−24 V 1.02 × 10^−24 V 3.02 × 10^−24 V
A dc power line for a light-rail system carries 1000 A at an angle of 30.0∘ to Earth's 5.0 × 10 −5 T field. What is the force on a 100-m section of this line? 4.30 N 2.50 N 3.00 N 3.30 N
By how many percent is the torque of a motor decreased if its permanent magnets lose 5.0% of their strength? 10.0% 2.5% 5.0% 0%
What is the maximum torque on a 150-turn square loop of wire 18.0 cm on a side that carries a 50.0-current in a 1.60-T field? 300 Nm 389 Nm 320 Nm 450 Nm
What is the force per meter on a lightning bolt at the equator that carries 20,000 A perpendicular to Earth's 3.0×10 −5 T field? 5.500 N/m 0.600 N/m 0.400 N/m 0.500 N/m
A physicist is designing a cyclotron to accelerate protons to one-tenth the speed of light. The magnetic field will have a strength of 1.5 T. Determine the rotational period of the circulating protons. Positive charge of a proton is 1.6 × 10 −19 C Mass of a proton is 1.67 × 10 −27 6.4 × 10^−8 s 8.4 × 10^−8 s 4.4 × 10^−8 s 2.4 × 10^−8 s
The cross-sectional dimensions of the copper strip shown are 2.0 cm by 2.0 mm. The strip carries a current of 100 A, and it is placed in a magnetic field of magnitude B = 1.5 T. What is the value of the Hall potential in the copper strip? Negative charge of an electron = 1.6 × 10^−19 C 7.4 × 10^−6 5.8 × 10^−6 6.2 × 10^−6 4.3 × 10^−6