Unit 2 Physics Test Review Guide
1) What is the difference between speed and velocity?
Velocity includes a direction, speed does not
2) Describe all the possible ways an object can accelerate?
Increase speed, decrease speed, change direction
3) How are velocity and acceleration related to one another?
Acceleration is a measure of change of velocity
4) How do you tell the units for velocity and acceleration and speed apart?
Speed has no direction (45 mph, 3.2 m/s)
Velocity has direction (37 mph west, +1.5m/s)
Acceleration has 2 units of time (9.8 m/s2, 9 mph/s)
5) When do you use the d= ½ at2 formula?
When an acceleration and time are given
6) How could you calculate the acceleration due to gravity on Earth?
Find time and distance, rewrite the formula
A=2d/t2
7) What happens to the speed of a cart traveling down an inclined plane? What would a
graph of this motion look like?
The speed increases as it travels down the ramp, D/T graph would be a curve
going up.
The V/T graph would be straight line with a positive slope
8) What happens to the acceleration of a cart traveling down an inclined plane? What
would a graph of this motion look like?
The acceleration would be constant, a flat line at whatever rate velocity was
increasing.
9) What is the speed of an object traveling 450km in 208 min. in km/hr?
V=d/t
T = 208 min / 60 = 3.47 hr
V=450 km/3.47 hr
V=129.68 km/hr
10)What distance has an object traveled in 6s at a constant speed of 9m/s?
V=d/t
9 m/s = d/6 sec
9 m/s * 6 sec = d
54 m = d
11)How long will it take a car to travel 40miles going 65mph?
V=d/t
65 mph = 40 mi/t
t=40 mi/65 mph
t=.62 hr or 36.9 min
12)What is the acceleration of an object that starts from rest and accelerates to 37mph in
7s?
A=(Vf-V0)/t
V0 =0 mph
Vf = 37 mph
t = 7 sec
A=(37mph – 0 mph)/7 sec
A = 5.29 mph/sec
13)What is the acceleration of a bike that slows down from 8m/s to a stopped position in
1 minute?
A=(Vf-V0)/t
V0 =8 m/s
Vf = 0 m/s
t = 60 sec
A=(0 m/s – 8 m/s)/60 sec
A = -0.13 m/s2
OR
A=(Vf-V0)/t
V0 =8 m/s
Vf = 0 m/s
t = 1 min
A=(0 m/s – 8 m/s)/1 min
A = -8 m/s/min
14)What is the average speed of a runner who goes 5 miles in 38 minutes, stops to rest
for two minutes, and then goes 2 more miles in 15 minutes?
Vavg = total distance/total time
Vavg = 7 mi/55 min
Vavg =0.127 mi/min
15)Graph the story above (in 14) and calculate the runner’s speed during the first part of
his graph.
V=d/t
V=5 mi/38 min
V=0.132 mi/min
Distance (mi)
distance vs time
6
4
distance
2
0
0
20
40
60
Time (min)
16)What kind of graph represents speed? Acceleration? BE ABLE TO DO THESE BOTH!
Speed is distance vs time
Acceleration is speed vs time
17)What is meant by “freefall” acceleration?
Falling without anything besides gravity working on it (no wind resistance)
18)What is the name of the force that causes an object in freefall to accelerate?
Gravity – acceleration due to gravity
19)What is the acceleration due to gravity on earth?
9.8 m/s2
20)What force works against gravity during freefall?
Wind or air resistance works against gravity
21)What does “terminal velocity” mean? When does an object reach terminal velocity?
Terminal velocity is the maximum velocity a falling object will reach. Wind
resistance will prevent the object from getting any faster. Terminal velocity is
reached when acceleration due to gravity and deceleration due to wind
resistance balance each other (equilibrium)
22)If an object that has a mass of 30g falls for 4s, what is its velocity at the end of 4s?
What is its acceleration?
Acceleration is gravity (9.8 m/s2)
A=(Vf-V0)/t
V0 =0 m/s
Vf = ?
t = 4 sec
A= 9.8 m/s2
9.8 m/s2=(Vf-0 m/s)/4 s
4s * 9.8 m/s2 = Vf
39.2 m/s = Vf
23)What distance has a skydiver traveled if at the end of a 5s freefall? What is their
velocity at this point? What is their average speed?
D=1/2at2
D = ½ (9.8 m/s2)(5 s)2
D = ½ (9.8 m/s2)(25 s2)
D = 122.5 m
A=(Vf-V0)/t
V0 =0 m/s
Vf = ?
t = 5 sec
A= 9.8 m/s2
9.8 m/s2=(Vf-0 m/s)/5 s
5s * 9.8 m/s2 = Vf
49 m/s = Vf
Average speed = distance/time
Average speed = 122.5 m/5 sec
Average speed = 24.5 m/s
24)Which object would reach the ground first, a bowling ball or a softball dropped from
10m? Explain your answer.
The same time – they have about the same wind resistance and mass ratio.
25)How would the speed of a tennis ball dropped from 1m compare to the same tennis
ball dropped from 10m? How would their accelerations compare?
The speed of the 10m drop would be more, unless the ball reaches terminal
velocity in 1 m – which is not very likely.
The acceleration would be the same until the ball reaches terminal velocity.