Work Energy and...

What is potential energy?

A physics student is performing a experiment in which she twirls  rubber stopper at the end of a string around in a circle at nearly constant speed and tries to determine its acceleration. Which of the following single changes would enables her to most nearly double the acceleration of the rubber stopper?

A ride in an amusement park called scream machine swings the riders around a complete vertical circle during the course of the ride.
Identify where on ride rider feels the maximum speed?

A ball of mass $$m$$ is attached with the string of length $$R$$, rotating in a circular motion, with instantaneous velocity $$v$$ and centripetal acceleration $$a$$.
Calculate the centripetal acceleration of the ball if its mass is doubled?

Identify the correct statement of Work-Energy Theorem : 

A simple pendulum, composed of a bob of mass $$m$$ connected to the end of a massless rod, executes simple harmonic motion as it swings through small angles of oscillation.The maximum angular displacement with the vertical is denoted by $${ \theta  }_{ max }$$. Frictional effects and variation of acceleration due to gravity are negligible.  
Which one of the following would enable you to calculate the length of the pendulum?

A ball with mass m and speed $$V_0$$ hit a wall and rebounds back with same speed.
Calculate the change in the object's kinetic energy.

A car and a lorry both are moving with equal kinetic energies. If equal braking force is applied on both, then before corning to rest: 

What is kinetic energy?

Which of the following will lead to a change in kinetic energy of a body?