Work, Energy and Power Physics - Work, Energy and Power

A boy “A” of mass 50 kg climbs up a staircase in 10 s. Another boy “B” of mass 60 kg climbs up a Same staircase in 15s. The ratio of the power developed by the boys “A” and “B” is

If the force F acting on a body as a function of x then the work done in moving a body from x = 1 m to x = 3m is

Two balls of equal masses moving with velocities 10 m/s and -7 m/s respectively collide elastically. Their velocities after collision will be

A bullet hits and gets embedded in a wooden block resting on a horizontal friction less surface. Which of the following is conserved?

Define spring constant of a spring.

A body is moving at constant speed over a frictionless surface. What is the work done by the weight of the body?

What happens to the P.E. of a bubble when it rises in water?

Name a process in which momentum changes but K.E. does not.

Does the P.E. of a spring decreases or increases when it is compressed or stretched?

Obtain the expressions for the velocities of the two bodies after collision in the case of one dimensional elastic collision and discuss the special cases.

Obtain an expression for the critical vertical of a body revolving in a vertical circle

An elevator which can carry a maximum load of 1800 kg (elevator + passengers) is moving up with a constant speed of 2 ms-1. The frictional force opposing the motion is 4000 N. Determine the minimum power delivered by the motor to the elevator in watts as well as in horse power.

A truck of mass 1000 kg accelerates uniformly from rest to a velocity of 15 ms-1 in 5 seconds. Calculate
(i) its acceleration,
(ii) its gain in K.E.,
(iii) average power of the engine during this period, neglect friction.

A body of mass 0.3 kg is taken up an inclined plane to length 10 m and height 5 m and then allowed to slide down to the bottom again. The coefficient of friction between the body and the plane is 0.15. What is the
(i) work done by the gravitational force over the round trip?
(ii) work done by the applied force over the upward journey?
(iii) work done by frictional force over the round trip?
(iv) kinetic energy of the body at the end of the trip?
How is the answer to (iv) related to the first three answers?