Chapters 8-9

Question 1

Who wrote Principia?

Answer 1

Newton

Question 2

According to Newton’s law of universal gravitation, what happens to the gravitational force as the distance between two objects increases?

Answer 2

Decreases

Question 3

Which of the following statements is true concerning friction?

Answer 3

Has direction opposite to motion

Question 4

What is the force of kinetic friction if the normal force is 18 lb and the coefficient of kinetic friction is .31?

Answer 4

5.6 lb

Question 5

What is the acceleration of an object with a mass of 10.5 kg if a 12 N force pushes the object horizontally across a surface? Neglect friction.

Answer 5

1.1 m/s^2

Question 6

What force is necessary to make a 52 kg object accelerate at 1.1 m/s2^? Neglect friction.

Answer 6

57 N

Question 7

Of the four fundamental forces, which holds the nucleus together?

Answer 7

Strong force

Question 8

Of the four fundamental forces, which is the weakest?

Answer 8

Gravitational force

Question 9

Of the fundamental forces which is the strongest?

Answer 9

Strong force

Question 10

Of the four fundamental forces, which is the attraction between different masses?

Answer 10

Gravitational force

Question 11

Completion:

A force is any …..?

Answer 11

Push or pull

Question 12

The statement that everybody maintains its present velocity unless the body is acted upon by an external force is known as …..?

Answer 12

Inertia

Question 13

For every action there is always an equal and opposite ……?

Answer 13

Reaction

Question 14

The …… fundamental force can be a force of repulsion.

Answer 14

Electromagnetic force

Question 15

A drawing that shows all of the forces acting on a body is called a(n) ……?

Answer 15

Free-body diagram

Question 16

The force that is equal in magnitude but opposite in direction to the resultant and achieves equilibrium in a system is called the …..?

Answer 16

Equilibrant

Question 17

When an object’s mass is at rest, it is called the object’s ….. mass.

Answer 17

Inertial mass

Question 18

The laws of planetary motion were developed by ……?

Answer 18

Kepler

Question 19

The first accurate value of G was calculated by ……

Answer 19

Cavendish

Question 20

A body that is not accelerating is said to be in ….. equilibrium.

Answer 20

Translational

Question 21

The process in which we can find the center of mass of an irregularly shaped object is called …..?

Answer 21

Multiple suspensions

Question 22

True/False:
According to the (principle of transmissibility) a vector may be applied anywhere along its line of action without changing its effect.

Answer 22

True

Question 23

Any object can be balanced on a sharp point positioned precisely beneath the object’s (center of gravity).

Answer 23

True

Question 24

A body acts as if all of its mass were concentrated directly at its (center of gravity).

Answer 24

True

Question 25

Force is (inversely) proportional to acceleration.

Answer 25

Directly

Question 26

Mass is (directly) proportional to acceleration.

Answer 26

Inversely

Question 27

A (Newton) is the force required to accelerate a mass of one kilogram at a rate of one meter per second squared.

Answer 27

True

Question 28

For a typical combination of surfaces u(s) is (larger) in value than u(k).

Answer 28

True

Question 29

The force a surface exerts perpendicularly against an object's weight is called the (normal force).

Answer 29

True

Question 30

When given an object's weight, you can find its mass by (multiplying) its weight by the rate of acceleration due to gravity.

Answer 30

Dividing

Question 31

(Forces) always occur in action-reaction pairs.

Answer 31

True

Question 32

An object is (stable) if it's center of mass falls outside its base of support.

Answer 32

Unstable

Question 33

The force transmitted along a rope or other connector is called (net force).

Answer 33

Tension

Question 34

Equations: | Newton's second law of motion

Answer 34

F=ma

Question 35

Universal law of gravitation

Answer 35

M1 • M2 F= G————— r^2

Question 36

Determines force of static friction

Answer 36

F(sf) = (u)s • F(N)

Question 37

Short Answer: | Define friction

Answer 37

Friction may be defined as the resistance arising when an object moves through a medium or across a surface.

Question 38

In your own words, state two of the four laws of kinetic friction.

Answer 38

#2. Kinetic friction is separate from velocity. #4 Kinetic friction is dependent on the component materials of the areas in connection.

Question 39

Name three of the four ways to reduce friction.

Answer 39

1. By reducing the roughness of the surface 2. By lubricating the surfaces 3. By using rollers, roller bearings, or ball bearings.

Question 40

Define stable and unstable equilibrium.

Answer 40

Stable equilibrium- An object in stable equilibrium is not easily tipped over. Unstable equilibrium- An object in unstable equilibrium is upset at the slightest disturbance.

Question 41

If a 55 N force is required to move an object that weighs 93 N across a level surface at a constant speed, what is the coefficient of kinetic friction?

Answer 41

Do math then

Question 42

How large a mass will 32 N accelerate at the same rate achieved by 13 N acting on 8.3 kg?

Answer 42

Set up proportion then

Question 43

If a box weighing 536 N is pulled forward at constant speed by a force of 150. N at an angle of 37.0 degrees with the ground, what normal force does the supporting surface exert on the box?

Answer 43

Review ch.9 review problem #6.

Question 44

A box weighing 87 lb is being pulled with a rope that exerts a force of 60. lb at an angle of 15 degrees with the horizontal. If the coefficient of kinetic friction is .35 what is the kinetic friction?

Answer 44

Look at ch. 9 review problem # 6

Question 45

Calculate the gravitational force between two masses of 455 kg and 625 kg, that are separated by 0.150 meters.

Answer 45

Use formula on card