Homework Helpers: Physics

1 Kinematics

 

Chapter 1 Examination

Part I—Matching

Match the following terms to the definitions that follow.

a. displacement

b. kinematics

c. velocity

d. free fall

e. scalar

f. acceleration

g. mechanics

h. vector

i. component vector

_____1. A quantity that can be described completely with numbers and units.

_____2. The branch of physics that deals with motion.

_____3. Speed in a particular direction.

_____4. One of a set of two or more vectors that can combine to form a resultant vector.

_____5. The rate at which an object changes its velocity.

_____6. The state of a falling object where the only unbalanced force acting on it is gravity.

Part II—Multiple Choice

For each of the following questions, select the best answer.

7. Which of the following is not an example of a vector quantity?

a) distance b) displacement c) velocity d) acceleration

8. Which of the following shows the correct units for acceleration?

a) m b) m/s c) m/s2 d) m2/s2

9. When an object with a velocity of zero experiences a negative acceleration, it will:

a) remain at rest

b) speed up

c) slow down

d) stop

10. A dog travels 3.0 m east, 6.0 m north, and 2.0 m south. What total distance did the dog travel?

a) 11.0 m

b) 6.0 m to the northeast

c) 9.0 m

d) 5.0 m

11. A dog walks 2.0 m north, 5.0 m south, and then 3.0 m north. What is the dog’s overall displacement?

a) 10.0 m

b) 0.0 m

c) 7.0 m south

d) 2.0 m east

12. An object in motion must experience a change in:

a) speed

b) acceleration

c) velocity

d) position

13. If a boy dropped a rock off a high cliff, how fast would it be falling after 2.0 seconds had elapsed? (Ignore air resistance.)

a) –2.0 × 101 m/s

b) 2.0 × 102 m/s

c) 35 m/s

d) –35 m/s

14. If an apple fell from a tree, how long would it take to reach a velocity of –3.00 m/s?

a) 3.00 s

b) 3.27 s

c) 2.94 s

d) 0.306 s

15. A car starts from rest and accelerates at a constant rate of 4.50 m/s2 until it reaches a velocity of 26.0 m/s. How far does it travel during this time?

a) 5.78 m

b) 21.5 m

c) 75.1 m

d) 94.8 m

Part III—Graphs

Base your answers to questions 16 through 18 on the Graph 1.9.

16. How fast is the car going at 2 seconds?

17. How far does the car travel in the first 3 seconds?

18. At what time does the car first stop?

19. During which time interval does the car have a negative velocity?

20. At 10 s, how far away is the car?

Graph 1.9

Part IV—Calculations

Perform the following calculations.

21. An apple with an initial velocity of 1.5 m/s rolls horizontally off the edge of a table with a height of 55 cm. How long will the apple be in the air, and how far from the edge of the table will it strike the ground? (Ignore air resistance.)

22. A car launches horizontally off the edge of a cliff with a height of 18.6 m. It strikes the ground below at a distance of 98.4 m away from the edge of the cliff. How fast was the car going when it flew off the edge of the cliff?

23. A golfer hits a golf ball with an initial velocity of 11.4 m/s at an angle of 43.0° above the horizontal. Assuming the ground in front of the golfer is level, and there is no air resistance, how far will the ball travel?

24. A truck with an initial velocity of 35.0 m/s experiences a constant acceleration of –6.5 m/s2 as the driver applies the brakes. How long does it take the truck to come to a complete stop?

25. A boy drops a water balloon off the top of his apartment building and counts how long it takes to hit the ground below. If he is able to count to “3 Mississippis” (approximately 3 seconds) before the balloon hits the ground, approximately (to one significant digit) how tall is the building?