Answer Window

The Motion Test consists of 12 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 quantity of 60 km/h describes a property of motion known as

(D). magnitude of velocity.
The velocity of a moving object tells you the speed and direction of a moving object, sometimes referred to as the magnitude and direction of motion. (Magnitude means a property that can be quantitatively described, such as the volume of a eraser or the length of a pencil.) Since a direction was not specified, the quantity given is the magnitude of velocity alone.














































Question #2: A ratio ofv/t is a measure of motion that is known as

(C). acceleration.
The delta symbol () means "change in," so v means "a change in velocity" and t means "a change in time." By definition, acceleration is a change of velocity per unit time, so v over t describes an acceleration.














































Question #3: A ratio of d/t is a measure of motion that is known as

(A). speed.
By definition, speed is a measurement of how fast something is moving (magnitude of velocity). It is defined as a change of distance per elapsed time -- or d over t.


















































Question #4: Ignoring air resistance, an object falling toward the surface of the earth has a velocity that is

(B). increasing.
Falling objects are uniformly accelerated by the force of gravity and all objects in free fall experience a constant acceleration. The acceleration is 9.8 m/s2, so during each second of fall an object gains a velocity of 9.8 m/s. Thus an object in free fall (meaning ignoring air resistance) has a velocity that is increasing during the fall.




















































Question #5: Ignoring air resistance, an object falling toward the surface of the earth has an acceleration that is

(A). constant.
Objects in free fall are uniformly accelerated by the force of gravity and experience a constant acceleration of 9.8 m/s2. Thus during each second of fall an object experiences an increase of speed of 9.8 m/s.




















































Question #6: A ball rolling across the floor slows to a stop because

(A). there are unbalanced forces acting on it.
Galileo understood that matter persists in its state of motion, and called the property inertia. Today, we understand that inertia describes the tendency of an object to remain in unchanging motion in the absence of an unbalanced force.




















































Question #7: After leaving the rifle, a bullet fired horizontally has how many forces acting on it (ignoring air resistance)?

(B). One, from the pull of gravity.
The force from the gunpowder explosion can act only while the expanding gases can push on the bullet, that is, when it is still inside the rifle. Once it leaves the rifle the only force acting on the bullet is gravity.





















































Question #8: What is a sprinter's speed if a distance of 200.0 m is covered in 21.4 s?

(D). 9.35 m/s

Click below to see one way to solve this problem.

Solution Motion 8
When you have finished with the solution screen, remember to click the "go away" button in the upper left or upper right corner.


















































Question #9: A pitcher throws a ball at 40.0 m/s and the ball is electronically timed to arrive at home plate 0.4625 s later. What is the distance from the pitcher to the home plate?

(B). 18.5 m

Click below to see one way to solve this problem.

Solution Motion 9
When you have finished with the solution screen, remember to click the "go away" button in the upper left or upper right corner.

















































Question #10: What is the velocity of a car that accelerates from rest at 9.0 feet per second squared for 8.0 seconds?

(C). 72 ft/s

Click below to see one way to solve this problem.

Solution Motion 10
When you have finished with the solution screen, remember to click the "go away" button in the upper left or upper right corner.

















































Question #11: A ball thrown straight up climbs for 3.0 seconds before falling. Neglecting air resistance, with what velocity was the ball thrown?

(C). (D). 29 m/s

Click below to see one way to solve this problem.

Solution Motion 11
When you have finished with the solution screen, remember to click the "go away" button in the upper left or upper right corner.

















































Question #12: A car with an initial velocity of 88.0 ft/s is able to come to a stop over a distance of 100.0 ft when the brakes are applied. How much time was required for the stopping process?

(B). 2.27 s

Click below to see one way to solve this problem.

Solution Motion 12
When you have finished with the solution screen, remember to click the "go away" button in the upper left or upper right corner.




O