MC	Physics	Standard: 01
Objective: 02. Analyze the motion of an object if terms of velocity, time, and acceleration.
ILO:

An object is observed to have zero acceleration. Which of the following statements must be true?

a. The object is motionless.

b. The object is moving in a circular path.

c. There is no friction acting on the object.

d. The object has a constant velocity.

Correct Answer: d

MC	Physics	Standard: 01
Objective: 02. Analyze the motion of an object if terms of velocity, time, and acceleration.
ILO:

A car driving down the freeway has a constant velocity. Which of the following statements must be true?

a. The car has zero acceleration.

b. The car is moving in a circular path.

c. There is no friction acting on the car.

d. The car is speeding up.

Correct Answer: a

MC	Physics	Standard: 01
Objective: 02. Analyze the motion of an object if terms of velocity, time, and acceleration.
ILO:

The following table gives the position of a boat at various times.

Position (m)	Time (s)
25	1
22.5	3
20	5
17.5	7
15	9
12.5	11

How can the motion of the boat best be described?

a. The boat has a constant, non-zero velocity.

b. The boat has zero velocity, but non-zero acceleration.

c. The boat has a constant, non-zero acceleration.

d. There is insufficient data here to accurately describe the boatÕs motion.

Correct Answer: a

MC	Physics	Standard: 01
Objective: 02. Analyze the motion of an object if terms of velocity, time, and acceleration.
ILO:

Which of the following graphs best represents the data in the table?

Time (s)	Velocity (m/s)
1	2
2	4
3	6
4	8

Correct Answer: b

MC	Physics	Standard: 01
Objective: 02. Analyze the motion of an object if terms of velocity, time, and acceleration.
ILO:

One of the oldest rides at an amusement park is the Merry-go-round. It is favorite of very young children, but not exciting enough for high school age students. There is still much physics that can be studied with the Merry-go-round. Consider the following Merry-go-round. The inner radius of the riderÕs platform is 10 ft. The outer radius is 20 ft. There are four rows of animals to ride in that 10 foot distance on the platform. When the Merry-go-round is moving at full speed it takes just 40 seconds to make a complete rotation. Some of the horses on the Merry-go-round move up and down in a periodic manner.

The horse on the innermost row of animals is located 12.0 ft from the center of rotation. The horse on the outermost row of animals is located 18.0 ft from the center of rotation.

Answer the following as it relates to the above.

1. The person riding on the inner horse would feel an acceleration that is

a. zero once the ride gets up to speed

b. the same as the acceleration of a person on the outer horse

c. about 2/3 the acceleration of a person on the outer horse

d. about 3/2 the acceleration of a person on the outer horse

2. The kinetic energy of a person riding on the inner row as compared to the kinetic energy of the same person riding on the outer row

a. is the same since they both take the same time to make one revolution.

b. is equal to the ratio of their respective radii of rotation.

c. is equal to the inverse ratio of their respective radii of rotation.

d. is equal to the ratio of the square of their respective radii of rotation.

Correct Answers:

1. d

2. d

I	Physics	Standard: 01
Objective: 02. Analyze the motion of an object if terms of velocity, time, and acceleration.
ILO:

One of the easier rides at a local amusement park is the steam engine driven train. The train follows the track shown in the diagram below. The total length of the track is 1.4 miles. It takes the train 12.0 minutes to cover the length of the track. The train takes 4 sec. from stop to reach its speed, which it then maintains through the entire course until it takes 6 sec. to stop back at the station.

Answer the following questions as they relate to the above.

1. If you are going to determine the force acting on you at point B on the track you will need to know all of the following except

a. the radius of curvature of the track at point B

b. the speed you are moving at point B

c. your mass

d. how long it took you to get to point B from the station.

2. The average velocity of the train during the 12 minute ride is

a. zero

b. 11.7 mi/hr

c. 7.0 mi/hr

d. 10.3 ft/s

3. The average speed of the train during the 12 minute ride is

a. zero

b. 11.7 mi/hr

c. 7.0 mi/hr

d. 10.3 ft/s

4. The acceleration a person riding the train would experience is

a. in almost opposite directions at points D and E

b. in almost opposite directions at points D and C

c. in almost the same direction at points B and E

d. only felt when starting and stopping the train.

Correct Answers:

1. d

2. a

3. c

4. c

P	Physics	Standard: 01
Objective: 02. Analyze the motion of an object if terms of velocity, time, and acceleration.
ILO:

1. A car of mass 1200 kg is driven around a circular track of radius 40 m at a speed of 30 m/s. What is the centripetal acceleration of the car?

2. The car given above in question 1 moves to a track of radius 80 m and travels at the same speed of 30 m/s.

a. What is the centripetal acceleration of the car?

b. At what speed could the car move and still have the same centripetal force as that found when the track had a radius of 40 m?

Correct Answers:

1. Acceleration = (velocity)2/(radius)

(30m/s²)2/(40m) = 22.5 m/s² 1 point

2. a. Acceleration = (velocity)2/(radius)

(30m/s²)2/(80m) = 11.25 m/s² 1 point

b. (mass)(velocity squared) / (radius) = centripetal force

(centripetal force)(radius) / (mass) = (velocity) ²

(2.7 E 4)(80)/ 1200 = 1800 = (velocity) ²

velocity = 1800 = 42.4 m/s 1 point

P	Physics	Standard: 01
Objective: 02. Analyze the motion of an object if terms of velocity, time, and acceleration.
ILO:

A vehicle is traveling at 5.0 m/s when it begins to accelerate at a rate of 0.75 m/s². The mass of the vehicle is 1200 kg.

1. How far will the vehicle travel before it has a velocity of 10 m/s?

2. How long will it take to be traveling at 10 m/s?

Correct Answers:

1. Distance = [(final velocity squared) ∆ (initial velocity squared)] / (twice acceleration)

(100-25) / 2(.75) = 50 m 1 point

2. (Change in velocity) / acceleration = time

(10-5) / 0.75 = 6.676 seconds 1 point