PHSC 101 Sun Chapter 1, 2 & 3 Homework
A tow truck exerts a force of 3000 N on a car that accelerates at 2 m/s^2. What is the mass of the car?
1500 kg
A tow truck exerts a force of 3000 N on a car, accelerating it at 2 m/s/s. What is the mass of the car?
1500 kg
A 2-kg mass that weighs 20 N has 40 J of potential energy relative to the ground. What is its height?
2 m.
If a freely falling object were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s^2, then its speed reading would increase each second by...
20 m/s.
A person is attracted toward the center of Earth by a 500-N gravitational force. The force of attraction of the Earth toward the person is...
500 N.
If a rocket initially at rest accelerates at a rate of 50 m/s^2 for 10 seconds, its speed will be...
500 m/s.
A 10-N falling object encounters 10 N of air resistance. Which statement is right? A. The object is moving faster and faster. B. The object has an acceleration of 10 m/s^2. C. The object is falling at a constant velocity. D. The object has an acceleration of zero. E. None
C and D.
Which has the greater momentum when moving? A. a container ship B. a bullet C. either of these depending on speed.
C.
What are the right units for work?
Joule and N*m
If an object has momentum, it must also have...
Kinetic Energy
What is the unit for weight?
Newtons.
When you catch a fast-moving baseball with your bare hand, a good idea is to catch it so that your hand stops it...
Slowly, so that the force on your hand will be small.
While a car travels around a circular track at a constant speed, which statement is right?
The car has a constant velocity.
Arnold Strongman and Suzie Small each pull on opposite ends of a rope in a tug-of-war. The greater force on the rope is exerted by...
same by each.
If both the mass and speed of an object are doubled, its momentum...
is quadrupled.
A block being pushed 8 N to the left and 4 N to the right will have a __ acceleration in magnitude, while a block being pushed 8 N to the left and to the right will have a __ acceleration in magnitude.
large; small.
When a cannon is fired, the accelerations of the cannon and cannonball are different because the...
masses are different.
An iron ball and wooden ball of the same size are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater...
momentum.
According to the definition of mechanical work, pushing on a rock accomplishes no work unless there is...
movement in the same direction as the direction of the force.
Which object has zero acceleration?
one at rest, one moving at constant velocity, and one at equilibrium.
When both the force and time of contact are doubled, the impulse on an object is...
quadrupled.
When an apple that weights 1 N is dropped and freely falls, the net force on the apple is...
1 N.
For a freely falling object dropped from rest, what is its velocity at the end of 10 seconds?
100 meters per second.
A baseball player bats a ball with a force of 1000 N. The ball exerts a reaction force against the bat of...
1000 N.
Jack has a mass of 100 kg, while Anna has a mass of 50 kg. They both stand at rest next to each other on frictionless ice. Suddenly Anna gives Jack a push. Which of the following statements is right?
-Anna will move faster than Jack. -They will move in opposite directions.
Which of the following physical quantities are vectors? A. Time B. Speed C. Acceleration D. Velocity E. Force F. Inertia G. None
-C. Acceleration -D. Velocity -E. Force
If you push an object at constant velocity, compare the friction force with the pushing force. What is correct?
-Friction force is equal to pushing force. -Friction force is in the opposite direction.
Match the statement with the right quantity. Energy associated with motion... Force applied for an amount of time... Energy associated with position... Rate at which work is done... Energy transferred by force... Mass in motion...
-Kinetic Energy -Impulse -Potential Energy -Power -Work -Momentum
What is the SI Units for each physical concept? Mass Volume Distance Force Acceleration Velocity Density
-Mass: kilograms -Volume: cubic meters -Distance: meters -Force: newtons -Acceleration: meters per second squared -Velocity: meter per second -Density: kilograms per cubic meter
Match the quantity with the right unit: Power Energy Impulse Force Momentum
-Power: Watt -Energy: Joule -Impulse: N * s -Force: kg * m/s^2 -Momentum: kg * m/s
While driving down the highway, a lovebug spatters onto your windshield. Which experiences the greater force of impact? Which undergoes the greater change in momentum during the time of contact? Which undergoes the greater impulse?
-both the same, but different consequences? -the lovebug? -both the same, but different consequences?
A block being pushed 8 N to the left and 8 N to the right would be under __. A block being pushed 8 N to the left and 4 N to the right would have a __ net force.
-equilibrium -large
The amount of friction that occurs when two blocks slide against each other depends on...
-how much they are pressed together -the "stickiness" of atoms on their surfaces -the kinds of material being pressed
An object travels 8 meters in the 1st seconds of travel, 8 meters again during the 2nd second of travel, and 8 meters again during the 3rd second. Its acceleration is...
0 m/s^2
What is the acceleration of a car that moves at a steady velocity of 100 kilometers per hour for 2 hours?
0 m/s^2
The amount of air resistance on a 0.8-N flying squirrel with terminal speed is...
0.8 N.
A 10-kg block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block in meters per second squared is...
1.
Match the forces with the right statement: 1. The force always exerted on an object from earth. 2. The force is always normal (perpendicular) to the contact surface. 3. The force is in the direction opposite to the moving direction.
1. Gravitational Force (Weight) 2. Support Force 3. Friction Force
Match the right Newton's Law of Motion with the statements. 1. The object starts to move from rest when a non-zero force is acted on the object. 2. The object at rest tends to remain at rest because of inertia. 3. When you are pulling a cart to the right direction, the cart is pulling you to the left direction.
1. Second law 2. First law 3. Third law
Jack has a weight of 500 N and he stands on a scale in an elevator moving upward from the first floor to the third floor. Compare the reading on the scale with your actual weight. 1. The moment when the elevator starts to move in an upward direction from rest. 2. When the elevator continues to move upward at a constant velocity. 3. The moment when the elevator stops at the third floor.
1. more than 500 N 2. equal to 500 N 3. less than 500 N
Starting from rest, the distance a freely falling object will fall in 0.5 seconds is about...
1.25 meters.
A 1-kg block of iron weighs about...
10 N.
The support force on a 10-N book that rests on a horizontal surface is...
10 N.
If you toss a ball straight upward at 40 m/s with no air resistance, 6 seconds later its speed is...
10 m/s
For a freely falling object from rest, what is its acceleration at the end of 5 seconds?
10 meters per second squared.
If you push on a heavy piece of furniture with a force of 10 newtons to the right and the furniture does not move. What is the magnitude and direction of friction force on the furniture?
10 newtons to the left.
At a baseball game, a ball of mass 0.1 kg moving at a speed of v=30 m/s is caught by a fan. If the ball is stopped in 0.03 seconds, what is the average force of the ball on the catcher's hand?
100 N
Two 100 N weights are attached to a spring scale. What will be the reading on the scale?
100 N
If you push a heavy piece of furniture with a force of 20 newtons to the right and the furniture slides in a constant speed in a straight line to the right, what is the magnitude and direction of friction force?
20 newtons to the left.
What is the travel distance of a car that moves at a steady velocity of 100 kilometers per hour for 2 hours?
200 kilometers.
A car has a mass of 1000 kg and accelerates at 2 m/s^2. What is the magnitude of the net force exerted on the car?
2000 N
If a rocket accelerates from rest at a rate of 50 m/s/s for 10s, the distance it will cover during this time is...
2500 m.
If a baseball being thrown goes from zero to 30 m/s in 0.1 s, what is its average acceleration?
300 m/s^2
If a ball rolls down an inclined plane and gains 4 m/s each second it rolls, its acceleration is...
4 m/s^2
A piece of rope is pulled by two people in a tug-of-war. Each pulls with 400 N of force. What is the tension in the rope?
400 N
Lucy Lightfoot stands with one foot on one bathroom scale and her other foot on a second bathroom scale. Each scale reads 200 N. Is Lucy's weight (gravitational force) with right direction?
400 newtons, downward direction.
When a 500-N parachutist opens his chute and experiences 800 N of air resistance, the net force on him is...
5 m/s^2.
What is the acceleration of a hamster when it increases its velocity from rest to 20 meters per second in 4 seconds?
5 meters per second squared.
A 1-kg ball has twice as much speed as a 10-kg ball. Compared with the 1-kg ball, the 10-kg ball has...
5 times as much momentum.
A 10-N falling object encounters 4 N of air resistance. The net force on it is...
6 N.
A 10-N falling object encounters 4 N of air resistance. The acceleration of this non-free fall object is...
6 m/s^2.
What is the average speed of a rabbit that runs a distance of 21 meters in a time period of 3 seconds?
7 meters per second squared.
Two cars of mass 800 kg (Car 1) and 1000 kg (Car 2) have a head-on collision and come to a standstill. Calculate the speed of the second car, given that the first car was moving at 10 m/s.
8 m/s
What is the net force on a box pushed to the right with 100 newtons of force while being pushed to the left with 20 newtons of force?
80 newtons to the right.
What is the acceleration for free fall?
9.8 meters per second squared.
Which of the following will affect the work needed to be done against gravity to lift an object? A. increasing the speed of lifting B. reducing the height difference C. lifting the object on the moon instead of on the Earth D. increasing the mass of the object E. all will affect
A & D??
A car races on a circular track at a constant speed of 6 meters per second. Which of the following statements are right? A. The car has an acceleration. B. The car has a constant velocity. C. They have the same volume. D. The car has a changing velocity. E. None
A and D
Compare 2 kilograms of water with 2 kilograms iron block. Which of the following statements are true? A. They have the same density. B. They have the same inertia. C. They have the same volumes. D. They have the same weight on earth. E. None
A, B, C, and D
Which of the following statements are right for Newton's Third Law? A. Action and reaction forces occur in pairs. B. The action force can exist without the reaction force. C. Action and reaction forces are equal in magnitude and opposite in direction. D. Action and Reaction forces always act on two different objects. E. None.
A, C, and D.
Which of the following are right about new force? A. Net force is always zero. B. Net force is a vector sum of all the forces exerted on the object. C. Net force is zero for the object moving at a constant speed in a straight line. D. Net force does not have a direction. E. Net force is zero for an object at rest. F. All the statements are wrong.
B. Net force is the vector sum of all the forces exerted on the object. C. Net force is zero for the object moving at a constant speed in a straight line. E. Net force is zero for an object at rest.
A bowling ball sits at rest and another bowling ball rolls down a lane at constant speed. Which ball, if either, is in equilibrium?
Both balls.
True or False: A heavy object and a light object that are put at the same height has the same potential energy.
False.
True or False: As an object freely falls, its acceleration increases.
False.
True or False: Kinetic Energy is conserved for both elastic and inelastic collision.
False.
True or False: Since action and reaction force are equal in magnitude and opposite in direction, they will always cancel with each other.
False.
True or False: The inertia of our text book on the moon is much less than on earth.
False.
During each second of free fall, the speed of an object...
Increases by the same amount.
John is standing in a bus and staring at his phone without holding any handle. When the bus suddenly stops, what is the reason for the phenomenon?
Inertia.
What name is given to the property by which objects resist changes in motion?
Inertia.
True or False: A crate is at rest on a horizontal floor, with nobody pushing. The friction force acting on the crate is zero.
True.
True or False: Force, Impulse, and Momentum are vectors.
True.
True or False: Jack has a mass of 100 kg, while Anna has a mass of 50 kg. They both stand at rest next to each other on frictionless ice. Suddenly Anna gives Jack a push, and they both start to move. Consider Jack and Anna as one system, the net force exerted on the system is zero.
True.
True or False: Momentum of system is always conserved for any kind of collision.
True.
A Mack truck and a Volkswagen traveling at the same speed have a head-on collision. The vehicle to undergo the greatest change in velocity will be the...
Volkswagen.
If gravity between the Sun and Earth suddenly vanished, Earth would continue moving in...
a straight line.
When you step off a bus moving at 2 m/s, your horizontal speed when you meet the ground is...
about 2 m/s.
A constant net force on a railroad car produces constant...
acceleration.
Disregarding air resistance, objects fall at constant...
acceleration.
As a flying squirrel falls faster and faster through the air...
air resistance increases, net force decreases, and acceleration decreases.
Consider a cart with a ball resting in its middle. When you quickly jerk the car forward, the...
back of the cart hits the ball.
Compared with a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much...
inertia, weight, volume, and mass.
A bullet is fired straight down from the top of a high cliff. Neglecting air resistance, the acceleration of the bullet is...
g.
A motor scooter undergoes acceleration when it...
gains speed, decreases speed, and changes direction.
In each second of free fall, the distance a freely falling object will travel is...
increasing.
An object has twice as much mass as another object also has twice as much...
inertia.
A moving object has...
speed, velocity, energy, and momentum.
When you toss a rock straight upward, which is no longer present at the top of its path?
speed.
The quantity that most relates to the size of an object is...
volume.
The force required to maintain an object at a constant velocity in free space is equal to...
zero.
The speed of a vertically-thrown ball at the top of its path is...
zero.
