Question 1

Use Figure 5-2 below to answer the following question(s).
 
-In Figure 5-2, showing a pendulum, at what position is the potential energy maximum?
A) A
B) B
C) C

Accepted Answer

The answer of Use Figure 5-2 below to answer the...

Question 2

Use Figure 5-2 below to answer the following question(s).
 
-In Figure 5-2, showing a pendulum, at what position is the kinetic energy maximum?
A) A
B) B
C) C

Accepted Answer

At point A, the pendulum is at its highest point and has no kinetic energy. As it swings down, it gains kinetic energy and reaches its maximum kinetic energy at point B, the bottom of its swing.

Question 3

A ball is released, from rest, at the left side of the loop-the-loop, at the height, h, as shown in Figure 5-3.
 
-Refer to Figure 5-3. If the radius of the loop is R, what minimum height h allows the ball not to fall off the track at the top of the loop?
A) 3.5 R
B)  R
C) 2.5 R
D) 2.0 R
E) 3.0 R

Accepted Answer

The answer of A ball is released, from rest, at...

Question 4

A ball is released, from rest, at the left side of the loop-the-loop, at the height, h, as shown in Figure 5-3.
 
-Refer to Figure 5-3. If the radius of the loop is R, what vertical height does the ball rise to, on the other side, neglecting friction?
A) 2R
B) greater than 2R
C) R
D) less than R

Accepted Answer

The answer of A ball is released, from rest, at...

Question 5

You slam on the brakes of your car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?
A) It would have skidded half as far.
B) It would have skidded 4 times farther.
C) It would have skidded twice as far.
D) It is impossible to tell from the information given.
E) It would have skidded  times farther.

Accepted Answer

The answer of You slam on the brakes of your...

Question 6

A 4-kg mass moving with speed 2 m/s, and a 2-kg mass moving with a speed of 4 m/s, are gliding over a horizontal frictionless surface. Both objects encounter the same horizontal force, which directly opposes their motion, and are brought to rest by it. Which statement correctly describes the situation?
A) Both masses travel the same distance before stopping.
B) The 2-kg mass travels farther, but not necessarily twice as far.
C) The 2-kg mass travels twice as far as the 4-kg mass before stopping.
D) The 4-kg mass loses more kinetic energy than the 2-kg mass.
E) The 4-kg mass travels twice as far as the 2-kg mass before stopping.

Accepted Answer

The answer of A 4-kg mass moving with speed 2...

Question 7

A horse-power is equal to 550
A) ft-lb/s.
B) J/hour.
C) Kw-h.
D) J/s.
E) ft-lb/minute.

Accepted Answer

A horse-power is equal to 550 foot-pounds per second (ft-lb/s).

Question 8

To accelerate your car at a constant acceleration, the car's engine must
A) maintain a constant turning speed.
B) maintain a constant power output.
C) develop ever-increasing power.
D) develop ever-decreasing power.

Accepted Answer

The car's engine must maintain a constant power output to accelerate the car at a constant acceleration.

Question 9

An auto is coasting on a level road. It weighs 10. kN. How much work is done by gravity as it moves horizontally 150. meters?

Accepted Answer

The answer of An auto is coasting on a level...

Question 10

Is more work required to increase a car's speed from rest to 30 mph, or from 50 mph to 60 mph?

Accepted Answer

The answer of Is more work required to increase a...

Question 11

A driver, traveling at 22. m/s, slows down her 1500. kg car to stop for a red light. What work is done by the friction force against the wheels?

Accepted Answer

The answer of A driver, traveling at 22. m/s, slows...

Question 12

A cyclist does work at the rate of 500. W while riding. With how much average horizontal force does the wheel push when she is traveling at 10. m/s?

Accepted Answer

The answer of A cyclist does work at the rate...

Question 13

A simple pendulum, with a 4.4 kg mass and length 75. cm, is released from rest at an angle of 50.°
(a) To what height does the mass swing on the other side?
(b) What is the speed of the mass at the bottom of the swing?

Accepted Answer

The answer of A simple pendulum, with a 4.4 kg...

Question 14

Assuming muscles are 20% efficient, at what rate is a 60. kg boy using energy when he runs up a flight of stairs 10. m high, in 8.0 s?

Accepted Answer

The answer of Assuming muscles are 20% efficient, at what...

Question 15

A roofer lifts supplies a height of 20. m with a hand-operated winch. How long would it take him to lift a 200. kg load, if the winch has an efficiency of 90%, and the rate at which the winch can do work is 0.80 hp?

Accepted Answer

The answer of A roofer lifts supplies a height of...

Question 16

A family goes on vacation for one week, but forgets to turn off an electric fan that consumes electricity at the rate of 200 watts. If the cost of electricity is $0.120/kW-h, how much does it cost to run the fan?

Accepted Answer

The answer of A family goes on vacation for one...

Question 17

When you lift a 12. ounce beverage can from the table top to your mouth, you do approximately how much work?
A) 1 Calorie
B) 1 erg
C) 1 Watt
D) 1 Kw-h
E) 1 Joule

Accepted Answer

Work is defined as the force applied to an object times the distance the object moves in the direction of the force. The unit of work in the International System of Units (SI) is the Joule (J). Lifting a 12-ounce beverage can from the table to your mouth involves moving the can against the force of gravity over a certain distance, which requires work measured in Joules, not in Calories (energy content of food), ergs (a much smaller unit of energy), Watts (a unit of power, or energy per time), or kilowatt-hours (a unit of energy typically used for electricity consumption).

Question 18

Matthew pulls his little sister Sarah in a sled on an icy surface (assume no friction), with a force of 60.0 Newtons at an angle of 37.0° upward from the horizontal. If he pulls her a distance of 12.0 m, the work he does is
A) 720 J
B) 185 J
C) 575 J
D) 0.333 kJ
E) 433 J

Accepted Answer

The work done is calculated using the formula: Work = Force × Distance × cos(θ). Here, the force is 60.0 N, the distance is 12.0 m, and the angle θ is 37.0°. Thus, Work = 60.0 × 12.0 × cos(37.0°) = 575 J.

Question 19

A 4.0 kg box of fruit slides 8.0 m down a ramp, inclined at 30.° from the horizontal. If the box slides at a constant velocity of 5.0 m/s, the work done by gravity is
A) 0.16 kJ.
B) -0.16 kJ.
C) -78. J.
D) zero.
E) +78. J.

Accepted Answer

The work done by gravity is equal to the change in potential energy of the box. The change in potential energy is given by:$$\Delta U = mgh$$where:* m is the mass of the box (4.0 kg)* g is the acceleration due to gravity (9.8 m/s^2)* h is the change in height of the box (8.0 m * sin(30°) = 4.0 m)Plugging in these values, we get:$$\Delta U = (4.0 kg)(9.8 m/s^2)(4.0 m) = 156.8 J$$Since the box is sliding at a constant velocity, the work done by gravity is equal to the work done by friction. Therefore, the work done by gravity is -156.8 J, which is closest to choice A) -0.16 kJ.

Question 20

A container of water is lifted vertically 3.0 m, then returned to its original position. If the total weight is 30. N, how much work was done?
A) No work was done.
B) 90 J
C) 45 J
D) 0.18 kJ
E) 0.90 kJ

Accepted Answer

Work is defined as the force applied to an object times the distance over which that force is applied, in the direction of the force. When the container is lifted and then returned to its original position, the net distance moved in the direction of the force (gravity) is zero, meaning no net work is done on the system.

Quiz 5: Work and Energy

Use Figure 5-2 below to answer the following question(s) . -In Figure 5-2, showing a pendulum, at what position is the potential energy maximum?

Use Figure 5-2 below to answer the following question(s) . -In Figure 5-2, showing a pendulum, at what position is the kinetic energy maximum?

A ball is released, from rest, at the left side of the loop-the-loop, at the height, h, as shown in Figure 5-3. -Refer to Figure 5-3. If the radius of the loop is R, what minimum height h allows the ball not to fall off the track at the top of the loop?

A ball is released, from rest, at the left side of the loop-the-loop, at the height, h, as shown in Figure 5-3. -Refer to Figure 5-3. If the radius of the loop is R, what vertical height does the ball rise to, on the other side, neglecting friction?

You slam on the brakes of your car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?

A horse-power is equal to 550

To accelerate your car at a constant acceleration, the car's engine must

An auto is coasting on a level road. It weighs 10. kN. How much work is done by gravity as it moves horizontally 150. meters?

Is more work required to increase a car's speed from rest to 30 mph, or from 50 mph to 60 mph?

A driver, traveling at 22. m/s, slows down her 1500. kg car to stop for a red light. What work is done by the friction force against the wheels?

A cyclist does work at the rate of 500. W while riding. With how much average horizontal force does the wheel push when she is traveling at 10. m/s?

A simple pendulum, with a 4.4 kg mass and length 75. cm, is released from rest at an angle of 50.° (a) To what height does the mass swing on the other side? (b) What is the speed of the mass at the bottom of the swing?

Assuming muscles are 20% efficient, at what rate is a 60. kg boy using energy when he runs up a flight of stairs 10. m high, in 8.0 s?

A roofer lifts supplies a height of 20. m with a hand-operated winch. How long would it take him to lift a 200. kg load, if the winch has an efficiency of 90%, and the rate at which the winch can do work is 0.80 hp?

A family goes on vacation for one week, but forgets to turn off an electric fan that consumes electricity at the rate of 200 watts. If the cost of electricity is $0.120/kW-h, how much does it cost to run the fan?

When you lift a 12. ounce beverage can from the table top to your mouth, you do approximately how much work?

Matthew pulls his little sister Sarah in a sled on an icy surface (assume no friction) , with a force of 60.0 Newtons at an angle of 37.0° upward from the horizontal. If he pulls her a distance of 12.0 m, the work he does is

A 4.0 kg box of fruit slides 8.0 m down a ramp, inclined at 30.° from the horizontal. If the box slides at a constant velocity of 5.0 m/s, the work done by gravity is

A container of water is lifted vertically 3.0 m, then returned to its original position. If the total weight is 30. N, how much work was done?