Physics-Balanced Forces

A box is being pushed by a constant force along a horizontal surface. If the object's velocity is constant, we can infer that there is _______ acting on the box A. a frictional force B. a net downward force C. no frictional force D. a net force upward E. a net force in the acceleration direction

A. a frictional force

Which force is directly responsible for your ability to walk, and to stop? A. weight B. kinetic friction C. static friction D. normal force E. applied force

C. static friction

An elevator of mass M is pulled upwards by a cable; the elevator has a positive, increasing, velocity. What is the tension in the cable (neglecting the mass of the cable)? A. less than zero B. between zero and Mg C. equal to Mg D. greater than Mg E. zero

D. greater than Mg

A net force F acts on a mass m and produces an acceleration a. What acceleration results if a net force 3F acts on mass 6m? A. a/2 B. 8a C. 4a D. 2a E. a/4

a. 8a

If the force of gravity suddenly stopped acting on the planets, they would a. continue moving straight in the direction they are traveling. b. fly straight away from the sun. c. continue to orbit the sun. d. spiral slowly away from the sun. e. spiral slowly towards the sun.

a. continue moving straight in the direction they are traveling.

Which Newton's law can explain the following statement that we often see on the highway display: "Buckle up -it's the State Law"? A. First Newton's Law B. Second Newton's Law C. Third Newton's Law D. Gravitational Law E. None from the above

a. first newton's law

The acceleration due to gravity is higher on Jupiter than on Earth. The mass and weight of a rock on Jupiter compared to that on Earth would be A. same, more B. same, less C. more, more D. more, less E. same, same

a. same, more

A passenger standing in a moving bus, facing forward suddenly falls backward. This can be an indication which of the following? a. the bus speeds up b. the bus slows down c. the bus doesn't change its velocity d. the bus turns to the right e. the bus turns to the left

a. the bus speeds up

You would have the largest mass of gold if you chunk of gold weighted 1 N on a. the moon. b. Jupiter. c. Sun d. Earth

a. the moon

The acceleration of an object is proportional to a. the net force acting on it b. its position c. its velocity d. its mass e. its displacement

a. the net force acting on it

If we know an object is moving at constant velocity, we may assume: a. the net force acting on the object is zero b. the object is gaining mass c. there are no forces acting on the object d. the object is accelerating e. the object is losing mass

a. the net force acting on the object is zero

The Earth pulls down on a railroad wagon with a force of 200 kN. Which of the following is the "reaction force"? A. The wagon pulls up the Earth with 200 kN B. The wagon pushes down the railroad with 200 kN C. The railroad pushes up the wagon with 200 kN D. The buoyant force pushes up the wagon with 200 kN E. The wagon pushes down the Earth with 200 kN

a. the wagon pulls up the earth with 200 kN

When a cat sleeps on a table, the net force on it is a. zero b. directed upward c. directed downward d. directed in the horizontal direction e. more information is required

a. zero

Which of the following is an example of a force which acts at a distance (without contact)? A. Tension B. Gravity C. Static friction D. Kinetic friction E. Normal force

b, gravity

If you exert a force F on an object which has a much greater mass than you do, the force which the object exerts on you will a. be of magnitude F and in the same direction b. be of magnitude F and in the opposite direction c. be of much less magnitude than F d. be of much greater magnitude than F e. be zero

b. be of magnitude F and in the opposite direction

An elevator of mass M is pulled upwards by a cable; the elevator has a positive, but decreasing, velocity. What is the tension in the cable (neglecting the mass of the cable)? A. less than zero B. between zero and Mg C. equal to Mg D. greater than Mg E. zero

b. between zero and Mg

Mass and weight a. both have the same measuring units b. both have different measuring units c. both represent force of gravity d. both represent measure of inertia e. none from the above

b. both have different measuring units

Action-reaction forces are A. equal in magnitude and point in the same direction B. equal in magnitude and point in opposite directions C. unequal in magnitude but point in the same direction D. unequal in magnitude and point in opposite directions E. cancel each other

b. equal in magnitude and point in opposite directions

. A soccer player kicks a soccer ball with a force of 1300 N. The soccer ball hits the player with a force of A. less than 1300 N B. exactly 1300 N C. more than 1300 N D. 0 N E. none from the above

b. exactly 1300 N

An object following a straight-line path at constant speed a. has no forces acting on it. b. has zero acceleration. c. none of the above. d. has a net force acting on it in the direction of motion. e. must be moving in a vacuum.

b. has zero acceleration.

If a book on the dashboard of your car suddenly flies towards you, the forward velocity of the car must have A. decreased B. increased C. changed direction to the right D. become zero E. changed direction to the left

b. increased

A karate chop delivers a blow of 3000 N to a board that breaks. The force that acts on the hand during that feat a. cannot be determined from the info given. b. is 3000 N. c. is less than 3000 N. d. is more than 3000 N.

b. is 3000 N.

A passenger standing in a moving bus, facing forward suddenly falls forward. This can be an indication which of the following? A. The bus speeds up B. The bus slows down C. The bus doesn't change its velocity D. The bus turns to the right E. The bus turns to the left

b. the bus slows down

A car traveling at 40 m/s strikes a mosquito. Which of the following is the true statement? A. The force on the mosquito is greater than the force on the car B. The force on the mosquito is equal to the force on the car C. The force on the mosquito is smaller than the force on the car D. The damage to the mosquito is equal to the damage to the car E. None from the above

b. the force on the mosquito is equal to the force on the car

Inertia can best be described as a. the force which keeps moving objects moving and stationary objects at rest. b. the tendency of any object to resist change and keep doing whatever it is doing. c. the willingness of an object to eventually lose its motion. d. the force which causes all objects to stop.

b. the tendency of any object to resist change and keep doing whatever it is doing.

The force required to maintain an object at a constant velocity in space is equal to a. the force required to stop the object b. zero c. the mass of the object d. the weight of the object e. none of the choices

b. zero

. A net force F accelerates a mass m with an acceleration a. If the same net force is applied to mass 5m, then the acceleration will be A. 5a B. 25a C. a/5 D. a/25 E. a/10

c, a/5

You and a friend are jumping on a trampoline. Why does Earth, which is rapidly orbiting around the sun, not move under your feet when you jump? Another words why do you land on the trampoline and it doesn't move away from you? a. there are different rules in space and on the surface of the earth b. Newton's 3rd law holds that there is an equal and opposite force exerted by the trampoline on your feet, which allow you to move with Earth through space. c. Newton's first law holds that your body moves along with Earth because it is not compelled to change its motion by an unbalanced force.

c. Newton's first law holds that your body moves along with Earth because it is not compelled to change its motion by an unbalanced force.

A railroad wagon pushes down on a railroad with a force of 200 kN. Which of the following is the "reaction force"? A. The wagon pulls up the Earth with 200 kN B. The wagon pushes down the railroad with 200 kN C. The railroad pushes up the wagon with 200 kN D. The buoyant force pushes up the wagon with 200 kN E. The wagon pushes down the Earth with 200 kN

c. The railroad pushes up the wagon with 200 kN

. A traffic light is suspended from a cable. Earth pulls downward on the traffic light with a force of 1500 N. If this is the "action force," what is the "reaction force"? A. The cable pulling upward on the traffic light with a 1500 N force B. The traffic light pulling downward on the cable with a 1500 N force C. The traffic light pulling upward on Earth with a 1500 N force D. Earth pulling downward on the cable with a 1500 N force E. The cable pulling up on Earth with a 1500 N force

c. The traffic light pulling upward on Earth with a 1500 N force

An elevator of mass M is pulled upwards at constant velocity by a cable. What is the tension in the cable (neglecting the mass of the cable)? A. less than zero B. between zero and Mg C. equal to Mg D. greater than Mg E. zero

c. equal to Mg

A ball is thrown straight up. At the top of its path, the magnitude of the net force acting on it is A. less than zero B. between zero and mg C. equal to mg D. greater than mg E. none from the above

c. equal to mg

As you slide a box at constant speed up a frictionless slope, pulling parallel to the slope, the tension in the rope will be: (draw a force diagram) a. greater than the weight of the box. b. equal to the weight of the box. c. less than the weight of the box. d. greater than the tension would be is the box were stationary.

c. less than the weight of the box.

When a baseball is struck by a bat, the force of the bat on the ball is equal and opposite to the force of the ball on the bat. This is an example of a. newton's first law b. newtons's second law c. newton's third law d. newton's law of gravitation e. none from the above

c. newton's third law

A loaded truck collides with a car causing huge damage to the car. Which of the following is true about the collision? a. the force on the truck is greater than the force on the car b. the force on the car is greater than the force on the truck c. the force on the truck is the same in magnitude as the force on the car d. during the collision the truck makes greater displacement than the car e. during the collision the truck has greater acceleration than the car

c. the force on the truck is the same in magnitude as the force on the car

A boy rides a bicycle at a constant velocity. Which of the following about the net force is true? A. There is a net force acting in the velocity direction B. There is a net force acting opposite to the velocity direction C. The net force is zero D. There is a net force acting perpendicularly to the velocity direction E. None from the above

c. the net force is zero

The law of inertia or Newton's 1st Law states that an object a. at rest will remain at rest unless acted on by an unbalanced force. b. will continue moving at the same velocity unless an unbalanced force acts on it. c. will do all of the options. d. that is not moving will never move unless a unbalanced force acts on it. e. will continue moving in a straight line unless an unbalanced force acts on it.

c. will do all of the options.

. A locomotive is pulling an empty freight car with a constant acceleration on a horizontal surface. The mass of the locomotive is five times the mass of the car. Which statement is true about the force applied by the car on the locomotive? A. 5 times greater than the force of the locomotive on the car B. 5 times less than the force of the locomotive on the car C. Zero since they move with a constant acceleration D. Equal to the force of the locomotive on the car E. More information is required

d. Equal to the force of the locomotive on the car

An object weighs 30 N on Earth. A second object weighs 30 N on the moon. Which has the greater mass? a. The one on Earth. b. Not enough information to say. c. They have the same mass. d. The one on moon.

d. The one on moon.

Earth pulls downward on a pen, of mass m, which is sitting on a table; the magnitude of the force is mg. If that is called the action force, what is the reaction force? A. The table pushing up on the pen with a force equal to mg B. The pen pushing down on the table with a force equal to mg C. The table pushing down on the floor with a force equal to mg D. The pen pulling upward on Earth with a force equal to mg E. The pen pulling up on the table with a force equal to mg

d. The pen pulling upward on Earth with a force equal to mg

The acceleration of an object is inversely proportional to a. the net force acting on it b. its position c. its velocity d. its mass e. its displacement

d. its mass

In the absence of a net force, a moving object will a. slow down and eventually stop b. stops immediately c. turn right d. move with constant velocity e. turn left

d. move with constant velocity

When the engines on a rocket ship in deep space, far from any other objects, are turned off, it will a. slow down and eventually stop b. stop immediately c. turn right d. move with constant velocity e. turn left

d. move with constant velocity

. Newton's third law refers to "action-reaction forces". These forces always occur in pairs and A. sometimes act on the same object B. always act on the same object C. may be at right angles D. never act on the same object E. always act at right angles

d. never act on the same object

A sheet of paper can be removed from under a container of milk without toppling it if the paper is jerked quickly. The reason this can be done is that a. none of the above b. gravity pulls very hard on the milk container. c. the milk container has very little weight. d. the milk container has inertia

d. the milk container has inertia

Compared to its mass on Earth, the mass of a 10-kg object on the moon is a. none of the choices b. less c. more d. the same

d. the same

If you flip a coin straight up into the air in a moving vehicle, which of these could NOT happen. (All answers describe motion relative to the vehicle.) a. the vehicle accelerates, and the coin flies backward b. the vehicle turns and the coin moves the opposite way c. the coin lands exactly where it started d. the vehicle slows down and the coin flies backward

d. the vehicle slows down and the coin flies backward

A hammer and a pebble are dropped simultaneously from the same height. Neglect air resistance. A. the hammer accelerates faster because it is heavier B. the hammer accelerates slower because it has more inertia C. the pebble accelerates faster because it has a smaller mass D. they both accelerate at the same rate because they have the same weight to mass ratio E. the pebble accelerates slower because it has a smaller mass

d. they both accelerate at the same rate because they have the same weight to mass ratio

The difference between mass and weight is: a. weight is a scalar quantity, while mass is a vector quantity. b. mass is a force, and weight is not. c. mass depends on gravity. d. weight depends on gravity. e. weight and mass are scalar quantities.

d. weight depends on gravity.

As a car moves forward on a level road at constant velocity, the net force acting on the tires is: a. greater than the normal force b. equal to the normal force c. less than the normal force d. zero

d. zero

In order for a rocket ship in deep space, far from any other objects, to move in a straight line with constant speed it must exert a net force that is a. proportional to its mass b. proportional to its weight c. proportional to its velocity d. zero e. proportional to its displacement

d. zero

After a cannonball is fired into friction less space, the amount of force needed to keep is going equals a. one half the fore with which it was fired b. twice the force with which it fired c. one quarter the force with which it was fired d. zero, since no force is necessary to keep it moving e. the same amount of force with which it was fired

d. zero, since no force is necessary to keep it moving

Compared to its weight on Earth, a 10-kg object on the moon will weigh a. the same amount b. more or less c. none of the choices d. more e. less

e. less

A spacecraft travels at a constant velocity in empty space far away from any center of gravity. Which of the following about the force applied on the spacecraft is true? A. The applied force is equal to its weight B. The applied force is slightly greater than its weight C. The applied force is slightly less that its weight D. The applied force must perpendicular to its velocity E. No applied force is required to maintain a constant velocity

e. no applied force is required to maintain a constant velocity

A passenger standing in a moving bus, facing forward suddenly falls to the right. This can be an indication which of the following? a. the bus speeds up b. the bus slows down c. the bus doesn't change its velocity d. the bus turns to the right e. the bus turns to the left

e. the bus turns to the left