Physics 1st Six Week Review 2013-2014
1. Definitions:
speed, velocity,average velocity, instantaneous velocity, distance, displacement, acceleration, frame of
reference, scalar, vector, resultant, projectile, scalar, vector
See your notes for these definitions.
2. What does slope represent on a displacement vs time graph? Velocity
What does slope represent on a velocity vs time graph? Acceleration
3. Draw displacement and velocity graphs showing constant motion, no motion, and acceleration.
See your notes-should have 9 graphs from the graphing activity we did.
4. Identify the following as scalar or vector quantities:
36° C: Scalar 15 cm: Scalar 5mph south:Vector +15m/s2:Vector
61 km/hr: Scalar
5. What 3 controls in an automobile can change acceleration?
Gas, brakes, steering wheel
6. What is the difference between average velocity, velocity, and instantaneous velocity?
Velocity is speed with direction, or a change in distance over time (with a direction). Average velocity is
an average of the velocity over a certain period of time. Instantaneous velocity is velocity at any given
moment (ex. Looking at your speedometer.)
7. A bowling ball and a ping pong ball are dropped from the same height while standing on the moon.
Which one lands first? (the moon has no atmosphere, it is a vacuum)
They should land at the same time. No air resistance.
8. Describe the relative velocity and acceleration of a ball as it is thrown into the air and drops to the
ground.
Acceleration remains constant (9.8m/s2 on earth), Velocity decreases as the ball moves away from the
earth, and increases as it moves back down. At the top of its path the velocity =0 m/s, and acceleration is
still 9.8 m/s2.
9. When do you use 9.8 m/s2 for a? When you are calculating the acceleration due to gravity on earth, or in
free fall equations.
Displacement-Time Graph
500
B
displacement (meters)
400
C
300
200
D
100
0
-100
Series1
A
-200
-300
-400
-500
0
10
20
30
40
50
60
70
80
90
100
time (seconds)
Velocity (m/s)
10. Refer to graph above describing a car in motion and answer the following:
a. What is the velocity of a car during the first 20seconds? (include units) rise/run (slope),
300-0/20-0=15m/s
Velocity vs. Tim e
b. What is the slope of segment CD? (include units) 0300/100-60= -7.5 m/s
6
c. What is the motion of the car during time 20s to time
4
60s? No Motion=no slope=no velocity
2
d. Which segment represents the greatest velocity?
Segment AB-steepest slope represents greater velocity.
0
-2
11. Refer to graph on the left describing a car in motion and
answer the following:
-4
-6
0
5
Tim e (s)
10
a. What does a line with a positive slope indicate on this graph? Increase in velocity, constant
acceleration
b. What would a line with a negative slope indicate on this graph? Decrease in velocity, constant
deceleration or negative acceleration.
c. What is the slope of the line shown (include units) 4-0/10-0= 0.4m/s2
d. What would a horizontal line (no slope) indicate on this graph? No acceleration, constant
velocity. If the horizontal line was at y=0, that would mean no velocity, constant position.
12. You start from home and walk 7 blocks east. You turn around and walk 3 blocks back towards your
house. What is your distance? What is your displacement in respect to your house? Can distance and
displacement ever be the same magnitude? Distance=10 blocks, Displacement=4 blocks east
Distance and Displacement can be the same if a) you don’t move, or b) you move away from your
starting point in a straight line and don’t turn around, or change directions.
13. A snail crawls 1.47cm in 95 seconds. What speed did the snail crawl?
S=d/t 1.47/95=0.015 cm/s
14. A truck enters the freeway at a velocity of 5.5 m/s and increases its velocity to 14.6 m/s in a time span
of 35 seconds. Calculate the acceleration of the truck.
a= vf-vi/t, 14.6-5.5/35, a=0.26 m/s2
15. A runner starts from rest and accelerates at a constant rate of .58 m/s2 for a distance of 25 meters. What
was the runners’ final velocity vf2=vi2+2ad, vf2=0+2 (.58)(25), vf2=29, vf=5.39m/s
16. A truck enters the freeway at a velocity of 5.5 m/s and accelerates at a constant rate of .78 m/s2 for a
period of 18 seconds. What was the trucks final velocity? a= vf-vi/t, .78= vf -5.5/18, 14.04= vf -5.5,
vf =19.54 m/s
17. A motorcycle is traveling at 9.6 m/s and accelerates uniformly to 15.8 m/s during a 10 second interval.
What is the total distance traveled by the motorcycle? Part 1: a= vf-vi/t  a=15.8-9.6/10, a=.62 m/s2
Part 2: vf2=vi2+2ad, 15.82=9.62+2(.62)d, d=127m
18. A stone is dropped from a bridge. How far does the stone fall after 5 seconds? d=vit+1/2at2,
d=1/2(9.8)(52), d=122.5m
19. You stand at the top of a cliff 88.5 meters above the ground. You drop a ball straight
downward. How many seconds does it take for the ball to hit the ground? d=vit+1/2at2, 88.5=1/2(9.8)t2,
2
t =18.06, t=4.25s
20. Using the graph to the right:
a. In which segment is the cart
accelerating? AB
b. In which segment is the cart
not moving? CD
c. In which segment is the cart
moving back towards the
start? DE
21. Using the diagram above:
a. What is the average speed from 0 to 1 seconds? S = d/t = 1cm/1s = 1 cm/s
b. What is the average speed from 1 to 2 seconds? S = d/t = 3cm/1s = 3 cm/s
c. What is the average speed from 2 to 3 seconds? S = d/t = 5cm/1s = 5 cm/s
d. What is the average speed from 3 to 4 seconds? S = d/t = 7cm/1s = 7 cm/s
e. What is the average speed from 4 to 5 seconds? S = d/t = 9cm/1s = 9 cm/s
f. What is the average speed from 0 to 5 seconds? S = d/t = 25cm/5s = 5 cm/s
g. What is the acceleration from 0 to 5 seconds? A = Vf – Vi/t = 5/5 = 1 cm/s2
22. What is frame of reference? Frame of reference is a fixed point used to determine direction and
magnitude of motion. It is the position from which the motion is being observed. Your frame of
reference affects the motion you perceive. If you are sitting still, you may having no motion relative to
the surface of the earth, but you are actually travelling at 30 km/sec relative to the sun.
23. When you are travelling in a car at 60 mph heading north,
a. What is the relative velocity of a signpost on the side of the road? 60 mph south
b. What is the relative velocity of a car passing you at 70 mph heading north? 10 mph north
c. What is the relative velocity of a car passing you at 60 mph heading south? 120 mph south
d. What is the relative velocity of your sister sitting next to you in the car? 0 mph (not moving)