You and your friends push a 400 kg piano across a hardwood floor at a constant speed. You all push it at a 30° angle below the horizontal. You and your friends expand a steady 2500 W for 10 s. If the coefficient of friction between the piano and the floor is 0.2, how far are you able to push the piano?

Pract

A net external force is applied to a 25-kg object that is initially moving at 1 m/s. The net force component along the displacement of the object varies with the magnitude of the displacement as shown in the drawing.   What is the final KE (in Joules) of the object at x=20m?   What is the speed (in m/s) of the object at x=20m?

A 7.80-g bullet moving at 530 m/s penetrates a tree trunk to a depth of 4.50 cm.  (a) Use work and energy considerations to find the average frictional force that stops the bullet. (b) Assuming the frictional force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment it stops moving.

Problem 10: The speed of a block traveling on a horizontal frictional surface changes from v; =16 m/s to v= 11 m/s in a distance of d = 8.5 m.

How much work is done when you push a crate horizontally with 120 NN across a 11-mm factory floor? Express your answer to two significant figures and include the appropriate units. WW = 1300 JJ If the force of friction on the crate is a steady 70 NN, find the KE gained by the crate. Express your answer to two significant figures and include the appropriate units.

A 7.80 g bullet is initially moving at 650 m/s just before it penetrates a tree trunk to a depth of 4.70 cm. (a) What is the magnitude of the average frictional force (in N) that is exerted on the bullet while it is moving through the tree trunk? Use work and energy considerations to obtain your answer.   b)  Assuming the frictional force is constant, how much time (in s) elapses between the moment the bullet enters the tree trunk and the moment it stops moving?

A particle of mass m moves along the x axis. Its position varies with time according to x = and t is in seconds. Determine the velocity v(t) of the particle as a function of t. Determine the acceleration a(t) of the particle as a function of t. Determine the power P(t) delivered to the particle as a function of t. Determine the work W done on the particle by the net force from t = 0 tot = t₁ in terms of defined variables and numerical constants. v(t) = a(t): = P(t) = W = 6t³ - 6t2, where x is in meters

A small sphere of mass m is launched horizontally over a body of water from a height h above the water and with a launch speed v0. Determine expressions for the following in terms of m, v0, h, and g. Air resistance is negligibly small. KEf is the final kinetic energy KEf of the projectile as it hits the water.

A small sphere of mass m is launched horizontally over a body of water from a height h above the water and with a launch speed v0. Determine expressions for the following in terms of m, v0, h, and g. Air resistance is negligibly small. W is the amount of work done by the force of gravity on the projectile during its flight. ΔKE is the change in kinetic energy ΔKE of the projectile from the time it was fired until it hits the water. KEf is the final kinetic energy KEf of the projectile as it hits the water.