Mechanical Energy

If you drop a light bulb on the floor and it shatters to pieces, will the mass of all the pieces together be the same as the mass of the bulb before it was dropped? Why or why not? (p.169)

(p. 170) The sum of kinetic energy and all forms of potential energy is called:

• mechanical energy

• elastic energy

• thermal mass

• gravity

ME = ?

(p. 170)

• KE + PE

• KE - PE

• KE²

• PE/2

(p.171) In the absence of friction, total mechanical energy:

• remains the same

• increases exponentially

• is lost as heat

• cannot be easily used

(p.171) Mechanical energy cannot change form.

• True

• False

As an egg falls to the ground, its potential energy is continuously converted into ________ energy. (p.171)

If an egg is thrown up in the air, its kinetic energy would be converted into gravitational __________ energy. (p.171)

In the absence of friction, initial mechanical energy equals _______ mechanical energy. (p.171)

Why doesn't the principle of mechanical energy conservation apply to situations in which frictional forces are present? (p.172)

Starting from rest, a child zooms down a frictionless slide from an initial height of 3.0 m. What is her speed at the bottom of the slide? Assume she has a mass of 25.0 kg.

(sample problem E, p.172)

• 7.7 m/s

• 6.3 m/s

• 75.0 m/s

• 1.3 m/s