1. Chapter 7 – Motion and Forces
Sample Math Problems
Chapter 7 – Motion and Forces

2. Question #15
An airplane traveling from San Francisco northeast to Chicago travels 1260 km in 3.5 hours. What is the airplane’s velocity?
v = d/t
v = 1260 km
3.5 hours
v = 360 km/h northeast

3. Question #16
Heather and Matthew take 45 s to walk eastward along a straight road to a store 72 m away. What is their average velocity?
v = d/t
v = 72 m
45 s
v = 1.6 m/s eastward

4. Question #17
Simpson drives his car with an average velocity of 85 km/h toward the east. How long will it take him to drive 560 km on a perfectly straight highway?
t = d/v
t = 560 km
85 km/h
t = h
t = 6.6 h

5. Question #18
Calculate the momentum of an 85 kg man jogging north along the highway at 2.65 m/s.
p = m*v
p = (85 kg)(2.65 m/s)
p = kg*m/s
p = 230 kg*m/s north

6. Question #20
A driver is traveling east on a dirt road when she spots a pothole ahead. She slows her car from 14.0 m/s to 5.5 m/s in 6.0 s. What is the car’s acceleration?
a = Δv/Δt
a = (5.5 – 14.0 m/s)
( s)
a = m/s2
a = -1.4 m/s2 east

7. Question #22
A 5.5 kg watermelon is pushed across a table. If the acceleration of the watermelon is 4.2 m/s2 to the right, what is the net force acting on the watermelon?
F = m*a
F = (5.5 kg)(4.2 m/s2)
F = 23.1 N
F = 23 N

8. Question #23
A block pushed with a force of 13.5 N accelerates at 6.5 m/s2 to the left. What is the mass of the block?
m = F/a
m = 13.5 N
6.5 m/s2
m = kg
m = 2.1 kg

9. Question #24
The net force on a 925 kg car is 37 N as it pulls away from a stop sign. Find the car’s acceleration.
a = F/m
a = 37 N
925 kg
a = 0.04 m/s2
a = m/s2
a = 4.0 x 10-2 m/s2 away from the stop sign

10. Question #25
A bag of sugar has a mass of 2.26 kg. What is its weight in newtons on the Earth?
On Earth, g = 9.8 m/s2
w = m*g
w = (2.26 kg)(9.8 m/s2)
w = N
w = 22 N