Answer Window

The Motion Patterns Test consists of 16 questions. Correct answers are found through links located at the end of each question. Answers for problems will have an additional link to a problem solution screen. If you bring up such a solution screen be sure to close it by clicking the button in the upper left corner or upper right corner.

The answer section is formatted for on-screen use, not printing, and will waste a lot of paper if printed directly.

Have a fun learning experience!














































Question #1: A change in the state of motion is evidence of

(B). an applied force that is unbalanced.

First, recall that any change in a state of motion is known as acceleration. From Newton's second law of motion, F = ma, you can see that an unbalanced force and acceleration are directly related. Then if the acceleration is zero then the net force must also be zero. Thus any change that occurs in the state of motion must mean that an unbalanced force was applied.














































Question #2: Considering the forces on the system of you and a bicycle as you petal the bike at a constant velocity in a straight line

(B). all forces are in balance.

From Newton's first law of motion we understand that an object moves at a constant velocity only when all the forces are balanced. The second law of motion, F = ma, also tells us that anytime the acceleration is zero the force is also zero, so all the forces must be in balance.














































Question #3: The extent of resistance to a change of motion is determined by an objects

(C). mass.

By definition, inertia is a resistance to a change in motion. Also by definition, mass is a measure of inertia. Thus the extend of resistance to a change of motion is determined by the mass of an object, which is measured in kilograms.


















































Question #4: With all other factors equal, if you double the unbalanced force on an object of a given mass the acceleration will be

(A). doubled.

Recall Newton's second law of motion is F = ma. Thus a = F/m, and we can see that the acceleration is directly proportional to the force. If you double the unbalanced force on an object of a given mass the acceleration will also be doubled. After all, is this not why a car with the most powerful engine will always have a greater acceleration if the cars are otherwise alike?




















































Question #5: With all other factors equal, If you double the mass of an object while a constant unbalanced force is applied, the acceleration will be

(C). half as much.

Again, recall that Newton's second law of motion is F = ma. Thus a = F/m, and we can see that the acceleration is inversely proportional to the mass when a constant unbalanced force is applied. Thus doubling the mass will result in 1/2 the acceleration.




















































Question #6: Which of the following is an unit that can be used for a measure of weight?

(B). newton

Weight is the force of gravity acting on a mass. From Newton's second law of motion (F = ma) we understand that the acceleration from the pull of gravity is g, and the weight (w) therefore is w = mg. The N is therefore the unit of weight (recall that the kg is an unit of mass, not weight).




















































Question #7: Which of the following is an unit for a measure of resistance to a change of motion?

(B). kg

As discussed in question three, inertia is a resistance to a change in motion. Also by definition, mass is a measure of inertia. Thus the extend of resistance to a change of motion is determined by the mass of an object, which is measured in kilograms.





















































Question #8: The immediate source of the force that accelerates a car over a road comes from

(C). the road.

From Newton's third law of motion we understand that every force is immediately matched by a second force that is equal in magnitude and opposite in direction. In addition, an acceleration always occurs in the same direction as an applied unbalance force (this is correct, isn't it?). So, the car pushes on the road and the road pushes back on the car, which accelerates it over the road. How else could it accelerate in a direction opposite to the direction it is pushing on the road?


















































Question #9: Doubling the distance between an orbiting satellite and the earth will result in what change in the gravitational attraction between the two?

(B). one-fourth as much

Newton's universal law of gravitation tells us the relationship between the force, or gravitational attraction, is inversely proportional to the square of the distance between two object. Thus doubling the distance between two object will result in 1/2 squared, or 1/4 the attraction.

















































Question #10: If a ball swinging in a circle on a string is moved twice as fast the force on the string will be

(B). four times as great.

The force varies with the square of the velocity of a ball moving is a circle. Thus if you move a ball twice as fast, two squared is four and the force will be four times as great.

















































Question #11: What net force is needed to accelerate a 1.25 kg book 5.00 m/s2?

(D). 6.25 N

Click below to see one way to solve this problem.

Solution Motion Pattern 11

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Question #12: What net force does the road exert on a 70.0 kg bicycle and rider in order to give them an acceleration of 2.0 m/s2?

(D). 140.0 N

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Solution Motion Pattern 12

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Question #13: A 1500 kg car accelerates uniformly from 44.0 km/hr to 80.0 km/hr in 10.0 s. What was the net force exerted on the car?

(C). 1500 N

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Solution Motion Pattern 13

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Question #14: What is the weight of a 70.0 kg person?

(B). 686 N

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Solution Motion Pattern 14

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Question #15: A 1,000.0 kg car at rest experiences a net force of 1,000.0 N for 10.0 s. What is the final speed of the car?

(A). 10.0 m/s

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Solution Motion Pattern 15

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Question #16: On Earth, an astronaut and equipment weigh 1960.0 N. While weightless in space, the astronaut fires a 100 N rocket backpack for 2.0 s. What is the resulting velocity of the astronaut and equipment?

(B). 1 m/s

Click below to see one way to solve this problem.

Solution Motion Pattern 16

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