Mechanics II

Obtain the potential, kinetic, and mechanical energy relative to the location A on Krusty’s new

rollercoaster. Use the supports on the side to determine the relative height.

A:100% Potential + 0 % Kinetic = 100% Mechanical

B:______Potential + ______Kinetic = ______Mechanical

C:______Potential + ______Kinetic = ______Mechanical

D:______Potential + ______Kinetic = ______Mechanical

E:______Potential + ______Kinetic = ______Mechanical

F:______Potential + ______Kinetic = ______Mechanical

G:______Potential + ______Kinetic = ______Mechanical

Where is Krusty going the fastest?

Which column shows conservation of energy?

In order to perform the following trick to the mobsters. What should

be the minimum velocity? Assume Krusty and Homer are each 100 kg

and that the radius of the arc is 2 m.

Is it possible?

Conceptual Questions

“Conservation of Energy”

  1. When an environmentalist asks to “conserve energy”, he or she really means:

a)Save energy

b)Save a specific form of energy

c)Solve a physics problem keeping energy constant

d)Give me your money for the green cause!

  1. A chocolate chip cookie has about 8 times more energy than TNT (dynamite), why aren’t cookies dangerous?

a)TNT is much more powerful than a cookie

b)The energy from cookies cannot be released

c)Energy is abstract, you cannot compare the energy contents

d)They ARE dangerous, haven’t you given sweets to kids!

  1. Football defensive backs love to smack receivers by transfering their kinetic energy. If a defensive back can run twice as fast as another with the same mass, how much harder can he hit?

a)Same

b)Twice as hard

c)Four times as hard

d)It depends … show me the money!

  1. If you carry a bag of groceries to the 2nd floor, how much more work do you do than when you carry them to the 1st floor?

a)Same

b)Twice as much

c)Four times as much

d)None … you carry the groceries!

  1. Why does the force of gravity does no work on a bowling ball rolling along a bowling alley?

a)There is no force of gravity acting on the bowling ball

b)The work done by gravity is canceled by the work done by the normal force

c)The bowling ball is moving perpendicular to the force of gravity

d)Gravity cannot do work ... you silly

  1. A stone is dropped from a certain height and penetrates into mud. All else being equal, if it is dropped from four times the height, how much farther should it penetrate?

a)Same

b)Twice as much

c)Four times as much

d)... mud war!

  1. You and your friend toss a ball back and forth in an airplane in flight. Does the kinetic energy of the ball depend on the speed of the airplane?

a)It depends on your frame of reference

b)No because you are moving with the ball

c)Yes because the total velocity of the ball is higher

d)Physics on vacations … just what I need!