PSCI Quiz 3

Question 1

The energy an object has because of its motion is called potential energy

Answer 1

False

Question 2

Your electric bill for 1500 kilowatt-hours is a charge for the power you have used that month.

Answer 2

False

Question 2

The watt (W) is a unit of

Answer 2

Power

Question 2

The amount of energy produced by power-generating dams is

Answer 2

decreasing, as more energy is used but new dams are not being built.

Question 3

While exploring an ancient Mayan tomb, you discover that the walls are closing in on you. By exerting 400 N of force, you are able to keep the wall from coming closer. The work you are doing on the wall is

Answer 3

zero, because the wall is not moving.

Question 4

Energy sources used today are mostly in what form of energy?

Answer 4

chemical

Question 5

A car traveling 20 mph can stop in about 53 ft. If the same car were traveling twice as fast, its stopping distance would be roughly

Answer 5

The kinetic enery is proportional to the velocity squared. If the velocity doubles, the kinetic energy increases by a factor of 4. The braking distance is directly proportional kinetic energy.

Therefore braking distance is 4 times the original distance.

Question 6

A force of 3,415 N is exerted on a 1,132 N car while moving it a distance of 2.7 m. How much work was on the car? Your answers should be in Joules

Answer 6

9,221

Work = Force * distance

Question 7

A crane does 192,812 J of work in raising a 1,325 kg load straight up. How high was the load lifted in meters?

Answer 7

14.8

Work = Force * distance = mass * ag * distance

distance = Work / (mass * 9.8 m/s2)

Question 8

How much work can be done by a 71.9 gram bullet traveling at 427 m/s? Units should be in Joules.

Answer 8

6,555

Work = Kinetic Energy

Must convert mass from grams into kilograms

K.E. = 1/2 * mass * velocity^2