Forces
If an object Is sliding down an inclined plane with friction, which direction does the friction force point in the free body diagram?
A) Down the incline, opposite to motion.
B) up the incline, opposite to motion
C) perpendicular to the incline , towards the surface
D) Vertically upward
B) Up the incline, opposite to motion.
1)A student pushes a cart with a constant force of 20 N. The cart has a mass of 10 kg. Using
Newton’s Laws, which explanation best describes how the force affects the cart’s acceleration?
A. The cart will not accelerate because the force is balanced.
B. The cart accelerates at 2 m/s² because acceleration depends on both force and mass.
C. The cart accelerates at 20 m/s² because acceleration equals the applied force.
D. The cart moves at a constant velocity because Newton’s First Law says objects resist
changes in motion.
B. The cart accelerates at 2 m/s² because acceleration depends on both force and mass.
A 1.0-kilogram rubber ball traveling east at 4.0 meters per second hits a wall and bounces back toward the west at 2.0 meters per second. Compared to the kinetic energy of the ball before it hits the wall, the kinetic energy of the ball after it bounces off the wall is
a) one-half as great b) one-fourth as great c) four times as great d) the same
b) one-fourth as great
What is the momentum of a 83 kg object moving with a constant velocity of 57 m/s?
0.687 kg*m/s
4731 kg*m/s
1.46 kg*m/s
140 kg*m/s
4731 kg*m/s
A 5 kg mass hangs from a rope. What is the tension in the rope if the mass is at rest?
A)24.5N
B) 5.0N
C) 49.0N
D)9.8N
c) 49.0N
If the net force on an object is zero, what would be its
acceleration?
A. Less than zero
B. Exactly zero
C. More than zero
D. It could be more or less depending on the situation
B. Exactly zero
Which action would require no work to be done on an object?
a) holding the object stationary above the ground
b) pushing the object along a horizontal floor against a frictional force
c) lifting the object from the floor to the ceiling
d) decreasing the speed of the object until it comes to rest
a) holding the object stationary above the ground
Which will have a larger momentum when moving at the same speed: a 2,000-kg truck or a 1,000-kg sedan?
A: The truck because it has a larger mass
B: The sedan because it has a smaller mass
C: They both have the same momentum only depends on speed
D: There is not enough information given in the problem
A: The truck because it has a larger mass
A box of mass 10 kg is pushed with a horizontal force of 50 N across a floor. If the
coefficient of kinetic friction is 0.2, what is the frictional force?
a) 10 N
b) 20 N
c) 50 N
d) 100 N
b)20
When the net force acting on an object is zero, what will its acceleration be?
a) Negative (less than zero)
b) Zero (no acceleration)
c) Positive (greater than zero)
d) It may vary depending on the circumstances
b) Zero (no acceleration)
A 2kg ball rolls off a 0.8m high table with an initial speed of 7 m/s. Ignore air resistance. As it first leaves the table, what is its kinetic energy?
49 J
16 J
11 J
7 J
49 J
A 10 kg cart with a momentum of 10 kg• m/s hits a 20 kg cart at rest. Momentum is calculated by using the formula p = mv, where m is the mass of an object and v is the velocity of an object. What is the momentum of the system after the collision?
A: 2 kg• m/s
B: 10 kg• m/s
C: 20 kg• m/s
D: 30 kg• m/s
B: 10 kg• m/s
A student pushes a box across the floor with a force of 12 N to the right. Friction
resists with 7 N to the left. Suddenly, another student begins to push the box with 10 N
to the left at the same time.
Which statement best describes the new net force and the box’s motion compared to
before?
a) The net force is 5 N to the right, so the box continues accelerating rightward but
more slowly.
b) The net force is 15 N to the left, so the box accelerates leftward, reversing its
motion.
c) The net force is 2 N to the left, so the box slows down and begins accelerating
leftward.
d) The net force is 22 N to the right, so the box accelerates much faster than before.
c)
The net force is 2 N to the left, so the box slows down and begins accelerating
leftward.
What is the weight of a 20 kg object on earth?
a)196kg
b)196N
c)20N
d)20kg
b)196N
As an object freely falls from a building, what happens to the energy of the object as it falls?
A. Its potential energy and kinetic energy increase.
B. Its potential energy and kinetic energy decrease.
C. Its potential energy increases and its kinetic energy decreases.
D. Its potential energy decreases and its kinetic energy increases.
D. Its potential energy decreases and its kinetic energy increases.
A student initially at rest on a frictionless frozen pond throws a 1 kg hammer in one direction. After the throw, the hammer moves off in one direction while the student moves off in the other direction. Which of the following correctly describes the above situation?
The hammer will have the momentum with the greater magnitude
The student will have the momentum with the greater magnitude
The hammer will have the greater kinetic energy
The student will have the greater kinetic energy
The hammer will have the greater kinetic energy
7)A child pulls a sled with a force of 12 N forward, while friction resists with 4 N
backward. What is the net force on the sled?
a) 8 N
b) 12 N
c) 16 N
d) 4 N
A) 8 N
6)A box of mass 10 kg is pushed to the right with a force of 40 N, while friction exerts a force of
10 N to the left. What is the box’s acceleration?
a) 0.5 m/s 2
b) 3.0 m/s 2
c) 4.0 m/s 2
d) 10.0 m/s 2
b) 3.0 m/s 2
A student swings a bat horizontally and makes contact with a ball. The ball leaves the bat, and the bat continues moving through the rest of the swing. Which of the following statements BEST describes the change in energy necessary to do work on the ball?
A. All the kinetic energy of the bat is converted to do work.
B. All the potential energy of the bat is converted to work.
C. Some of the Kinetic energy is converted to work
D. Some of the potential energy of the bat is converted to work.
C. Some of the Kinetic energy is converted to work
What is the impulse on a baseball bat that exerts a force of 250 N on a baseball for 0.15 seconds? I = F x t
0.15 N*s
37.5 N*s
250 N*s
1667 N*s
37.5 N*s