A small block of mass 250 g starts at rest at A, slides to B where its speed at point B is 6.50 m/s, then slides along the horizontal surface a distance 10.0 m before coming to rest at C. (a) What is the work of friction along the curved surface? Wf = J (Don't forget to use the correct sign!) (b) If the curved distance is 7.50 m, then estimate the average friction force on the block. f = N (c) What is the coefficient of kinetic friction along the horizontal surface? μk =
A block with mass 430 g is initially at rest as it compresses a spring with a force constant of 1300 N/m by 5.10 cm. After release, the block encounters a rough floor such that the coefficient of kinetic friction between the block and floor is 0.120. How far does the block travel across the rough floor before coming to rest? d =
In the figure R1 = 5.06 Ω, R2 = 15.2 Ω, and the ideal battery has emf ε = 11.4 V. (a) What is the magnitude of current i1? (b) How much energy is dissipated by all four resistors in 0.522 min? (a) Number Units (b) Number Units
A coil with an inductance of 2.1 H and a resistance of 14 Ω is suddenly connected to an ideal battery with ε = 100 V. At 0.085 s after the connection is made, what is the rate at which (a) energy is being stored in the magnetic field, (b) thermal energy is appearing in the resistance, and (c) energy is being delivered by the battery? (a) Number Units (b) Number Units (c) Number Units
A flywheel turns through 34 rev as it slows from an angular speed of 4.3 rad/s to a stop. (a) Assuming a constant angular acceleration, find the time for it to come to rest. (b) What is its angular acceleration? (c) How much time is required for it to complete the first 17 of the 34 revolutions? (a) Number Units (b) Number Units (c) Number Units
A man stands on a platform that is rotating (without friction) with an angular speed of 0.359 rev/s; his arms are outstretched and he holds a brick in each hand. The rotational inertia of the system consisting of the man, bricks, and platform about the central axis is 4.09 kg⋅m2. If by moving the bricks the man decreases the rotational inertia of the system to 1.13 kg⋅m2, (a) what is the resulting angular speed of the platform and (b) what is the ratio of the new kinetic energy of the system to the original kinetic energy? (a) Number Units (b) Number Units
A 0.49-kg metal sphere oscillates at the end of a vertical spring. As the spring stretches from 0.12 m to 0.23 m (relative to its unstrained length), the speed of the sphere decreases from 5.7 to 3.2 m/s. What is the spring constant of the spring?
The system in the figure below is in equilibrium, with the string in the center exactly horizontal. Block A weighs 42.0 N, block B weighs 49.0 N, and angle ϕ is 31.0∘. What are Find (a) tension T1, (b) tension T2, (c) tension T3, and (d) angle θ. (a) Number Units (b) Number Units (c) Number Units (d) Number Units
What multiple of the time constant τ gives the time taken by an initially uncharged capacitor in an RC series circuit to be charged to 81.5% of its final charge? Number Units
The figure shows a two-ended "rocket" that is initially stationary on a frictionless floor, with its center at the origin of an x axis. The rocket consists of a central block C (of mass M = 6.00 kg) and blocks L and R (each of mass m = 1.60 kg) on the left and right sides. Small explosions can shoot either of the side blocks away from block C and along the x axis. Here is the sequence: (1) At time t = 0, block L is shot to the left with a speed of 2.90 m/s relative to the velocity that the explosion gives the rest of the rocket. (2) Next, at time t = 0.70 s, block R is shot to the right with a speed of 2.90 m/s relative to the velocity that block C then has (after the second explosion). At t = 3.10 s, what are (a) the velocity of block C (including sign) and (b) the position of its center?
What multiple of the time constant T gives the time taken by an initially uncharged capacitor in an RC series circuit to be charged to 82.1% of its final charge? Number Units
The switch in the figure is closed on a at time t = 0. What is the ratio EL/E (a) just after t = 0 and (b) at t = 2.10 TL? (c) At what multiple of TL will EL/E = 0.500?
The body in the figure is pivoted at O. Three forces act on it in the directions shown: FA = 8.60 N at point A, 7.90 m from O; FB = 17.0 N at point B, 4.80 m from O; and FC = 19.0 N at point C, 4.40 m from O. Taking the clockwise direction to be negative, what is the net torque about O? Number Units
The figure shows a closed surface. Along the flat top face, which has a radius of 3.0 cm, a perpendicular field B→ of magnitude 0.40 T is directed outward. Along the flat bottom face, a magnetic flux of 0.50 mWb is directed outward. What are the (a) magnitude and (b) direction (inward or outward) of the magnetic flux through the curved part of the surface? (a) Number Units (b)