## 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/s^{2} d) m^{2}/s^{2}

__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 × 10^{1} m/s

b) 2.0 × 10^{2} 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/s^{2} 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/s^{2} 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?