Newton’s Laws Problems
1) When you sit on a chair, the resultant force 8) An object of mass m sits on a flat table. The
on you is 1) _______ Earth pulls on this object with force mg, which
A) depending on your weight. we will call the action force. What is the
B) up. reaction force? 8) _______
C) zero. A) The table pushing down on the floor with
D) down. force mg.
B) The object pushing down on the table with
2) In the absence of an external force, a mov ing C) The object pulling upward on the Earth with
object will 2) _______ force mg.
A) go faster and faster. D) The table pushing up on the object with force
B) slow down and eventually co me to a stop. mg.
C) stop immediately.
D) move with constant velocity.
9) A stone is thrown straight up. At the top of
its path, the net force acting on it is 9) _______
3) You are standing in a moving bus, facing A) instantaneously equal to zero.
forward, and you suddenly fall forward as the B) equal to its weight.
bus comes to an immed iate stop. What force C) greater than zero, but less than its weight.
caused you to fall forward? 3) _______ D) g reater than its weight.
A) normal force due to your contact with the
floor of the bus
B) force due to frict ion between you and the 10) The force that keeps you fro m sliding on an
floor of the bus icy sidewalk is 10) ______
A) static frict ion. B) normal force.
D) There is not a force leading to your fall. C) weight. D) kinetic friction.
11) It's more d ifficu lt to start moving a heavy
4) The acceleration of an object is inversely
proportional to 4) _______ carton fro m rest than it is to keep pushing it with
A) its velocity. constant velocity, because 11) ______
B) its mass. A) < .
C) the net force acting on it. B) in itially, the normal force is not perpendicular
D) its position. to the applied force.
C) the normal force is greater when the carton is
5) If you blow up a balloon, and then release it, at rest.
the balloon will fly away. This is an illustration D) < .
of 5) _______
A) Newton's second law.
12) An object sits on a frictionless surface. A
B) Newton's first law.
16-N force is applied to the object, and it
C) Galileo's law o f inertia.
D) Newton's third law. accelerates at 2.0 m/s 2. What is the mass of the
object? 12) ______
A) 4.0 kg B) 32 kg C) 8.0 kg D) 78 N
6) Action-reaction forces 6) _______
A) always act on the same object.
B) sometimes act on the same object. 13) Two horizontal forces act on a 5.0-kg mass.
C) may be at right angles. One force has a magnitude of 8.0 N and is
D) always act on different objects. directed due north. The second force toward the
east has a magnitude of 6.0 N. What is the
acceleration of the mass? 13) ______
7) A 20-ton truck collides with a 1500-lb car
A) 2.0 m/s 2 at 53 m E of N B) 1.6 m/s 2 due
and causes a lot of damage to the car. Since a lot
of damage is done on the car 7) _______ north
A) the truck did not slow down during the C) 2.0 m/s 2 at 53° N of E D) 1.2 m/s 2 due east
B) the force on the truck is greater then the force 14) The coefficient of static and kinetic frictions
on the car. between a 3.0-kg bo x and a desk are 0.40 and
C) the force on the truck is smaller than the force 0.30, respectively. What is the net force on the
on the car. box when a 15 N horizontal force is applied to
D) the fo rce on the truck is equal to the force on the box? 14) ______
the car. A) 8.8 N B) 6.2 N C) zero D) 12 N
15) A 10-kg bo x sitting on a horizontal surface
is pulled by a 5.0-N force. A 3.0-N friction fo rce
retards the motion. What is the acceleration of
the object? 15) ______
A) 0.30 m/s 2 B) 5.0 m/s 2 C) 0.50 m/s 2 D)
0.20 m/s 2