Kinetic Energy

The diagram shows a side view of a skateboard ramp. At which labeled points would the skateboarder have the most kinetic energy? W and X X and Y Y and Z W and Z

X and Y

The chart shows data for four different moving objects. Which shows the order of the objects' kinetic energies, from least to greatest? W, Y, X, Z Z, X, Y, W W, Y, Z, X X, Z, Y, W

X, Z, Y, W

What is the kinetic energy of a 620.0 kg roller coaster moving with a velocity of 9.00 m/s? 2,790 J 5,580 J 25,100 J 50,200 J

25,100 J

The kinetic energy of an object with a mass of 6.8 kg and a velocity of 5.0 m/s is J. (Report the answer to two significant figures.)

85

Kinetic energy is the energy an object has due to its

Motion

The mass of an object with 500 J of kinetic energy moving with a velocity of 5 m/s is kg. (Report the answer to one significant figure.)

40

Kinetic energy and mass are _________________ proportional.

Directly

Lenny wrote the steps he used to find the mass of an object with 400 J of energy moving at a velocity of 8 m/s. 1. Find the square of 8 m/s, which is 64 m2/s2. 2. Divide kinetic energy, 400 J, by 64 m2/s2, which is 6.25 J per m2/s2. 3. Divide 6.25 J per m2/s2 by 2 to get a mass of 3.125 kg. Which best describes Lenny's error? In Step 1, he should have found the square root of 400 J instead of squaring 8 m/s. In Step 1, he should have multiplied 8 m/s by 2 instead of squaring it. In Step 2, he should have divided 64 m2/s2 by 400 J instead of dividing 400 J by 64 m2/s2. In Step 3, he should have multiplied 6.25 J per m2/s2 by 2 instead of dividing it by 2.

In Step 3, he should have multiplied 6.25 J per m2/s2 by 2 instead of dividing it by 2.

If all else is constant, which would cause the greatest increase in kinetic energy of a moving object? Mass and velocity are each reduced by one-half. Mass is reduced by one-half, and velocity is doubled. Mass is doubled, and velocity is reduced by one-half. Mass and velocity are each doubled.

Mass and velocity are each doubled.

A 20.0 kg object is at rest, and then speeds up to 16.0 m/s. How much work was done on this system? 320 J 2,560 J 2,880 J 5,120 J

NOT 320 J

What does it mean when work is positive? Velocity is greater than kinetic energy. Kinetic energy is greater than velocity. The environment did work on an object. An object did work on the environment.

The environment did work on an object.

According to the work-energy theorem, the amount of work done can be determined using which formula? W = KE = 2m(v2i-v2f) W = KE = 1/2m(v2i-v2f) W = KE = 2m(v2f-v2i) W = KE = 1/2m(v2f-v2i)

W = KE = 1/2m(v2f-v2i)

The work-energy theorem states that the work done on an object is equal to a change in which quantity? kinetic energy displacement potential energy mass

kinetic energy

Which best summarizes a concept related to the work-energy theorem? When work is positive, the environment does work on an object. When work is negative, the environment does work on an object. When work is positive, the kinetic energy in a systemremains constant. When work is negative, the kinetic energy in a system remains constant.

When work is positive, the environment does work on an object.

Four vehicles are traveling on the same road. Which vehicle most likely has the greatest kinetic energy? a compact car traveling at a velocity of 10 m/s a pickup truck traveling at a velocity of 25 m/s a minivan traveling at a velocity of 10 m/s a motorcycle traveling at a velocity of 25 m/s

a pickup truck traveling at a velocity of 25 m/s

Which formula can be used to find velocity if kinetic energy and mass are known? v = (square root)1/2(KE)(m) v = (square root)2m/KE v = (square root)KE(m) v = (square root)2KE/m

v = (square root)2KE/m