Potential Energy

Equation for gravitational potential energy?

Ug = mgy, where y is the height above whatever we choose to call y=0

Is gravitational potential energy a scalar or vector?

Scalar, just like ALL quantities related to energy

Is work a scalar or a vector?

A scalar, because work is change in energy and all quantities related to energy are scalars.

If there is no external force that does work then the initial mechanical energy is equal to

the final mechanical energy, there is no change in mechanical energy.

Is there external work on a ball–Earth system for an ideal pendulum?

No

What is the work done by gravity when you raise a mass m by an amount h?

When a conservative force acts as a system moves from state a to state b…

How much potential energy is there in a spring stretched by an amount x?

What is F(x), force, in terms of U, potential energy?

If given U(x), how to find F(x)?

F(x) = -U’(x)

U = 0 is ___

arbitrary

When no external forces act, a system reconfigures to a ____ U

lower

Gravitating objects tend to move from _____ separation

large to smaller

Then for any value R, Ug is…

< 0

What is the Ug when there are more than 2 objects in a system?

An equilibrium point is when the potential energy is at a ____ or ____ and the force is ____

maximum, minimum, zero

What is unstable equilibrium and where is in the graph of U(x)

What is stable equilibrium and where is in the graph of U(x)

What is neutral equilibrium?

Why do systems tend to reconfigure towards lower U? (Your explanation should involve force somehow…)

On a potential energy vs. position graph, how do you find where an object’s speed is maximum?