# PHYSICS QUIZ #4

### 37 terms by Lizbethgrc28

#### Study  only

Flashcards Flashcards

Scatter Scatter

Scatter Scatter

## Create a new folder

A) the first law

A) zero.

### 3) In the absence of an external force, a moving object will

D) move with constant velocity.

### 4) When the rocket engines on the starship NO-PAIN-NO-GAIN are suddenly turned off, while traveling in empty space, the starship will

D) move with constant speed.

D) zero

### 6) You are standing in a moving bus, facing forward, and you suddenly fall forward. You can imply from this that the bus's

A) velocity decreased.

### 8) A constant net force acts on an object. Describe the motion of the object.

constant acceleration

its mass

a/2

2a

### If you blow up a balloon, and then release it, the balloon will fly away. This is an illustration of

Newton's third law

### Two cars collide head-on. At every moment during the collision, the magnitude of the force the first car exerts on the second is exactly equal to the magnitude of the force the second car exerts on the first. This is an example of

Newton's third law.

D) always be F.

### 15) Action-reaction forces

D) always act on different objects.

### 16) Action-reaction forces are

B) equal in magnitude but point in opposite directions.

### 17) A 20-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

B) the force on the truck is equal to the force on the car.

### An object of mass m sits on a flat table. The Earth pulls on this object with force mg, which we will call the action force. What is the reaction force?

D) The object pulling upward on the Earth with force mg.

### 19) A child's toy is suspended from the ceiling by means of a string. The Earth pulls downward on the toy with its weight force of 8.0 N. If this is the "action force," what is the "reaction force"?

D) The toy pulling upward on the Earth with an 8.0-N force.

### 20) A golf club hits a golf ball with a force of 2400 N. The golf ball hits the club with a force

B) exactly 2400 N.

### 21) Your bat hits the ball pitched to you with a 1500-N instantaneous force. The ball hits the bat with an instantaneous force, whose magnitude is

C) exactly equal to 1500 N.

### 22) State Newton's three laws.

Newton's first law: Every object continues in its state of rest, or of uniform velocity in a
straight line, as long as no net force acts on it.
Newton's second law: The acceleration of an object is directly proportional to the net
force acting on it, and is inversely proportional to its mass. The direction of the
acceleration is in the direction of the net force acting on the object.
Newton's third law: Whenever one object exerts a force on a second object, the second
exerts an equal force in the opposite direction on the first.

### 23) Mass and weight

C) are two different quantities.

### 24) The acceleration due to gravity is lower on the Moon than on Earth. Which of the following is true about the mass and weight of an astronaut on the Moon's surface, compared to Earth?

B) Mass is same, weight is less.

B) weight.

### 26) Who has a greater weight to mass ratio, a person weighing 400 N or a person weighing 600 N?

C) Neither; their ratios are the same.

### 27) A stone is thrown straight up. At the top of its path, the net force acting on it is

D) equal to its weight.

### 28) A 20-N weight and a 5.0-N weight are dropped simultaneously from the same height. Ignore air resistance. Compare their accelerations.

D) They both accelerate at the same rate because they have the same weight to mass ratio.

B) exactly mg

A) less than mg

### 32) The force that keeps you from sliding on an icy sidewalk is

C) static friction.

D) mk < ms.

### 34) A horizontal force accelerates a box from rest across a horizontal surface (friction is present) at a constant rate. The experiment is repeated, and all conditions remain the same with the exception that the horizontal force is doubled. What happens to the box's acceleration?

A) It increases to more than double its original value.

### 35) A packing crate slides down an inclined ramp at constant velocity. Thus we can deduce that

A) a frictional force is acting on it.

C) Mg cos q.

### 37) A block of mass M slides down a frictionless plane inclined at an angle q with the horizontal. The normal reaction force exerted by the plane on the block is directed

C) perpendicular to the plane.

### 38) A block of mass M slides down a frictionless plane inclined at an angle q with the horizontal. The gravitational force is directed

D) toward the center of the Earth.

Example: