Dr. Campbell

15 HW Review Mechanics #1.docx 6 October 2015

1

Physics Homework Review Mechanics #1

Name

Period

The equations:

Speed = time

Distance Velocity =

time

ntDisplaceme=

t

x

∆

∆=

12

12

tt

xx

−

−

Acceleration = t

v

∆

∆=

12

12

tt

vv

−

− Range = σ2±X

1. A car is traveling along the x-axis as depicted below in the position vs. time graph.

a. What is the average velocity between 20s and 60 s?

b. What is the instantaneous velocity at t = 30s? at t =15s?

c. During which time interval(s) does the car have a negative velocity?

d. At what time(s) does the car stop?

e. What is the position of the car at t = 50s?

f. At what time(s) does the car have a position of 30 m?

g. What does the straight line between 40s and 60s indicate?

h. During which time period(s) does the particle have the greatest speed?

i. What is the displacement of the car?

j. What is the distance the car traveled?

k. What was the speed of the car over the first 40 seconds?

Dr. Campbell

15 HW Review Mechanics #1.docx 6 October 2015

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2. The velocity vs. time graph is shown below for a car traveling north and south. The car has a

position of x = 20 m at t = 0s.

a. What is the average acceleration of the car over the first 50 seconds?

b. What is the instantaneous acceleration of the car at 10s? At 50s?

c. What is the displacement of the car over the first 80s?

d. What is the distance the car traveled over the first 80s?

e. What is the x-position of the car at 80s? at 120s?

f. During which time(s) does the car have positive acceleration?

g. What does the flat line between 40 seconds and 80 seconds indicate?

h. What is the instantaneous velocity of the car at 50s?

i. What does the straight line between 0s and 20 s indicate?

3. Sketch what the position vs. time and velocity vs. time graph would look like for the

following directions.

a. Starting at a position of -2.0 m, you walk slowly, for 10 seconds, away from the origin

with a constant velocity, ending at -12.0 m.

b. You stand still for 10 seconds.

c. You walk back towards the origin, for 10 seconds, with a increasing velocity, ending

at 0.0m.

d. You continue walking on the other side of the origin, for 10 seconds, with an

decreasing velocity, ending at +10.0 m.

e. Indicate whether the displacement, velocity and acceleration are positive, zero, or

negative for each of the segments.

Dr. Campbell

15 HW Review Mechanics #1.docx 6 October 2015

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4. A car is traveling along the x-axis as depicted below in the position vs. time graph. Sketch

what the velocity vs. time graph would look like.

5. Doc is pacing in front of the class. He moves 14 ft left, 20 ft right, 6 ft left, 10 ft right and

finally 10 ft left.

a. What is the displacement of Doc?

b. What is the distance that Doc traveled?

6. A car is traveling at 45 miles per hour. How long in minutes would it take for the car to travel

120 miles?

7. Round the following numbers to 3 significant figures.

a. 136420

b. 0.0014678

8. Perform the following calculations making sure the final answer has the correct number of

significant figures.

a. 172.34 + 8.6741 + 2.452 =

b. 74.32 x 1.02 x 0.5 =

c. (42.3)3 =

d. 14.0 + (4.3)(0.21) =

e. )416.16)(000.2(

)52.3()2.16( 22+

=

Dr. Campbell

15 HW Review Mechanics #1.docx 6 October 2015

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9. The velocity vs. time graph is shown below for a car traveling north and west. The car has a

position of x = 20 m at t = 0s. Sketch what the position vs. time graph would look like.

10. An object moves on a number line below. The filled circle on the left is the starting position

at -3m. The object moves to the right and the position is recorded each 2 seconds. Each vertical

line represents a separation of 1m. When the object get to the right side it stops (solid object)

and changes direction and moves to the left (boxes). The solid box represents the final position

of the object.

a. Determine the average speed over the entire journey.

b. Determine the average velocity over the first 10 seconds.

11. Given the vectors as shown below answer the following questions.

Starting at +5 m determine the resultant displacement for;

(Vector C) + (Vector B) – 2x (Vector A).

Work

Resultant

A B C

0 m 15 m -10 m

0 m 15 m -10 m

Dr. Campbell

15 HW Review Mechanics #1.docx 6 October 2015

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12. The following drawings indicate the motion of a ball subject to one or more forces on

various surfaces from right to left. Each circle represents the position of the ball at succeeding

instants of time. Each time-interval between successive positions is equal.

Rank each case from the highest to lowest velocity based on the ball’s second to last velocity

using the coordinate system specified in the figures. Note: Zero is greater than negative, and

ties are possible.

Highest 1. 2. 3. 4. 5. 6. Lowest