# Work Energy and Power

Disclaimer: This page is designed to complement and supplement your lecture notes/textbooks. It is not a complete learning package by itself.

Work

What do you calculate the work done by a constant force? Since work is a scalar quantity, does the direction of the force matter? (xmphysics)

Sometimes work done on an object does not result in changes in KE of the object. How is that possible? (xmphysics)

For the work-energy framework to work, KE, GPE and Elastic PE must be given appropriate formula. Can you derive the formula for

Principle of Conservation of Energy

When applying PCOE to solve problems, we usually have to decide on a “before” and an “after” instant. Why must there be no work done by external forces between the two chosen points of motion? How do we deal with frictional forces when applying PCOE? (xmtutor)

Many problems can be solved by either using Newton’s Laws of Motion or PCOE. Why is PCOE the preferred method (especially when springs are involved)? (xmtutor)

A Bungee Jumper jumps. Sketch the graphs showing how KE, GPE and EPE vary with drop distance. When is the maximum KE attained? (xmtutor)

Power

A mass is acted upon by a constant force. Can derive the formula for the power delivered by the force? How does the power vary with time and displacement? (xmtutor)

Does an engine of constant (maximum) power deliver the same forward thrust at every speed? How does a car’s engine power limit its acceleration and top speed? (xmtutor)

Miscellaneous

What information can we get from a force-displacement graph? (xmtutor)

What information can we get from a energy(work)-displacement graph? (xmtutor)

Related

Magnetic Cannon (xmdemo)

Anti-gravity Tin (xmdemo)

The Blow Pipe Contest (yayaphysics)