PHY 121 EXAMS 1-4 QUESTIONS WITH VERIFIED
ANSWERS
2.1 When you sit on a chair, the resultant force on you is
down
up
zero
depending on your weight - Answers - Up
2.2 When the rocket engines on the starship NO-PAIN-NO-GAIN are suddenly turned
off, while traveling in empty space, the starship will
stop immediately
go faster and faster.
slowly slow down, and then stop.
move with constant speed. - Answers - move with constant speed.
1.1 Starting from city A, a car drives 250 miles east to city B, then 300 miles north to city
C, and finally 700 miles west to city D. What is the distance between city A and city D?
Question options:
600 mi
400 mi
500 mi
300 mi - Answers - 500mi
,2.3 A 15-ton truck collides with a 1500-lb car and causes a lot of damage to the car.
Since a lot of damage is done on the car
Question options:
the truck did not slow down during the collision.
the force on the truck is greater than the force on the car.
the force on the truck is equal to the force on the car.
the force on the truck is smaller tan the force on the car. - Answers - The force on the
truck is equal to the force on the car
2.4 A sports car of mass 1000 kg can accelerate from rest to 35 m/s in 1.3 s. What is
the average forward force on the car?
Question options:
1.9 × 10^5 N
2.6 × 10^2 N
2.7 × 10^4 N
3.9 × 10^3 N - Answers - 2.7x10^4
1.2 A new car manufacturer advertises that their car can go "from zero to sixty in 8 s".
This is a description of
Question options:
average acceleration
average speed
instantaneous acceleration
,instantaneous speed - Answers - Average Acceleration
2.5 Is it possible for an object moving with a constant speed to accelerate? Explain.
Question options:
Yes, if an object is moving it can experience acceleration
Yes, although the speed is constant, the direction of the velocity can be changing.
No, if the speed is constant then the acceleration is equal to zero.
No, an object can accelerate only if there is a net force acting on it - Answers - Yes,
although the speed is constant, the direction of the velocity can be changing
2.6 A packing crate slides down an inclined ramp at constant velocity. Thus we can
deduce that
Question options:
a net downward force is acting on it.
a frictional force is acting on it.
it is not acted on by appreciable gravitational force.
it may be accelerating - Answers - a frictional force is acting on it.
2.7 It's more difficult to start moving a heavy carton from rest than it is to keep pushing it
with constant velocity, because
Question options:
µs< µk
µs > µk
initially, the normal force is not perpendicular to the applied force.
the normal force is greater when the carton is at rest. - Answers - µs > µk
, 2.8 A wooden block slides directly down an inclined plane, at a constant velocity of 6.0
m/s. What is the coefficient of kinetic friction, if the plane makes an angle of 25° with the
horizontal?
Question options:
0.37
0.47
0.91
0.42 - Answers - .47
2.9 You are standing in a moving bus, facing forward, and you suddenly fall forward as
the bus comes to an immediate stop. What force caused you to fall forward?
Question options:
There is not a force leading to your fall
gravity
force due to friction between you and the floor of the bus
normal force due to your contact with the floor of the bus - Answers - There is not a
force leading to your fall
2.10 Sue and Sean are having a tug-of-war by pulling on opposite ends of a 5.0-kg
rope. Sue pulls with a 15-N force. What is Sean's force if the rope accelerates toward
Sue at 2.0 m/s2?
Question options:
3.0 N
5.0 N
25 N
ANSWERS
2.1 When you sit on a chair, the resultant force on you is
down
up
zero
depending on your weight - Answers - Up
2.2 When the rocket engines on the starship NO-PAIN-NO-GAIN are suddenly turned
off, while traveling in empty space, the starship will
stop immediately
go faster and faster.
slowly slow down, and then stop.
move with constant speed. - Answers - move with constant speed.
1.1 Starting from city A, a car drives 250 miles east to city B, then 300 miles north to city
C, and finally 700 miles west to city D. What is the distance between city A and city D?
Question options:
600 mi
400 mi
500 mi
300 mi - Answers - 500mi
,2.3 A 15-ton truck collides with a 1500-lb car and causes a lot of damage to the car.
Since a lot of damage is done on the car
Question options:
the truck did not slow down during the collision.
the force on the truck is greater than the force on the car.
the force on the truck is equal to the force on the car.
the force on the truck is smaller tan the force on the car. - Answers - The force on the
truck is equal to the force on the car
2.4 A sports car of mass 1000 kg can accelerate from rest to 35 m/s in 1.3 s. What is
the average forward force on the car?
Question options:
1.9 × 10^5 N
2.6 × 10^2 N
2.7 × 10^4 N
3.9 × 10^3 N - Answers - 2.7x10^4
1.2 A new car manufacturer advertises that their car can go "from zero to sixty in 8 s".
This is a description of
Question options:
average acceleration
average speed
instantaneous acceleration
,instantaneous speed - Answers - Average Acceleration
2.5 Is it possible for an object moving with a constant speed to accelerate? Explain.
Question options:
Yes, if an object is moving it can experience acceleration
Yes, although the speed is constant, the direction of the velocity can be changing.
No, if the speed is constant then the acceleration is equal to zero.
No, an object can accelerate only if there is a net force acting on it - Answers - Yes,
although the speed is constant, the direction of the velocity can be changing
2.6 A packing crate slides down an inclined ramp at constant velocity. Thus we can
deduce that
Question options:
a net downward force is acting on it.
a frictional force is acting on it.
it is not acted on by appreciable gravitational force.
it may be accelerating - Answers - a frictional force is acting on it.
2.7 It's more difficult to start moving a heavy carton from rest than it is to keep pushing it
with constant velocity, because
Question options:
µs< µk
µs > µk
initially, the normal force is not perpendicular to the applied force.
the normal force is greater when the carton is at rest. - Answers - µs > µk
, 2.8 A wooden block slides directly down an inclined plane, at a constant velocity of 6.0
m/s. What is the coefficient of kinetic friction, if the plane makes an angle of 25° with the
horizontal?
Question options:
0.37
0.47
0.91
0.42 - Answers - .47
2.9 You are standing in a moving bus, facing forward, and you suddenly fall forward as
the bus comes to an immediate stop. What force caused you to fall forward?
Question options:
There is not a force leading to your fall
gravity
force due to friction between you and the floor of the bus
normal force due to your contact with the floor of the bus - Answers - There is not a
force leading to your fall
2.10 Sue and Sean are having a tug-of-war by pulling on opposite ends of a 5.0-kg
rope. Sue pulls with a 15-N force. What is Sean's force if the rope accelerates toward
Sue at 2.0 m/s2?
Question options:
3.0 N
5.0 N
25 N
