CH8: Newton's Laws of Motion

Question 1

Is force a spatial quantity?

Answer 1

Yes

Question 2

What did Aristotle [384 BC – 322 BC] do?

Answer 2

Aristotle used force to explain how motion could be created. Force is the impetus to motion.

Question 3

What did Galileo [1564 – 1642] do?

Answer 3

• Force causes change in velocity
• Gravity pulls an object towards the ground
• Effect of gravity is independent of an object’s mass

Question 4

What did Newton [1643 – 1727] do?

Answer 4

Developed mathematical formulations for force, including gravity

Question 5

What is a Force?

Answer 5

A push or pull exerted on one object by another object

Question 6

A force can attract or __________

Answer 6

repulse

Question 7

Do objects have to be in direct contact to exert a force?

Answer 7

No. – “Action at a distance” – gravity, electromagnetism

Question 8

Does exerting a force always cause a change in motion?

Answer 8

No. Exerting a force may or may not cause a change in motion. However, forces are acting all around us, with no motion present. Sometimes, forces are exerted to prevent motion from occurring.

Question 9

What are the four fundamental forces of the universe?

Answer 9

1. Strong
2. Electromagnetic
3. Weak Interaction
4. Gravity

Question 10

Strong force description:

Answer 10

Attraction
Relative Strength: 1
Range (m): 10^-15

Question 11

Electromagnetic force description:

Answer 11

Attraction or Repulsion
Relative Strength: 1/137
Range (m): Infinite

Question 12

Weak Interaction force description:

Answer 12

Attraction or Repulsion
Relative Strength: 10^-6
Range (m): 10^-18

Question 13

Gravity force description:

Answer 13

Attraction
Relative Strength: 6 x 10^-139
Range (m): Infinite

Question 14

What is the Earth’s mass?

Answer 14

5.9723 x 1024 kg

Question 15

What is the Earth’s radius?

Answer 15

~6371 km

Question 16

Two objects, both having mass, with a distance between the center of the objects (r). How does gravitational force come into play?

Answer 16

Object 1 will exert a force on object 2, and object 2 will exert a force on object 1. The amount of force exerted by object 1 on object 2 is equal in magnitude to the force exerted by object 2 on object 1. This is the gravitational force (Fg) that acts between these two objects.

Question 17

How to calculate gravitational force?

Answer 17

Fg = G(m1m2)/r^2

Question 18

Relationship between gravitational force and mass

Answer 18

Gravitational Acceleration is Mass Independent

Question 19

What are the two events in weightlifting?

Answer 19

1. The snatch
2. Clean and jerk

Question 20

What is the snatch?

Answer 20

Where a barbell is lifted from the ground to
above the head

Question 21

What is the clean?

Answer 21

Where a barbell is lifted from the ground to
above the shoulders

Question 22

What is Newton’s first law of motion?

Answer 22

Inertia & Equilibrium: The first law states that an object’s velocity is constant unless an unbalanced force is applied to the object.

Question 23

What is Newton’s second law of motion?

Answer 23

Dynamics: The second law states that when an unbalanced force is applied to an object, the velocity of the object will change. In other words, the object will accelerate.

Question 24

What is Newton’s third law of motion?

Answer 24

Force pairs: The third law states that forces act in pairs, where object A will exert a force on object B, and a force of equal magnitude and opposite direction will be exerted on object A by object B.

Question 25

What is equilibrium?

Answer 25

There is no change in velocity, therefore acceleration is 0. Since there is no net force acting on the object, there is no impulse applied and momentum does not change. In equilibrium, there may be forces acting on an object. However, the vector sum of these forces is equal to zero.

Question 26

What is static equilibrium?

Answer 26

A special condition of equilibrium occurs when velocity itself is zero

Question 27

What is inertia?

Answer 27

The resistance to a change in equilibrium. Inertia can take the form of mass, or moment of inertia. Equilibrium is maintained as objects have inertia.

Question 28

What is dynamics?

Answer 28

In dynamics, change in velocity is not zero, therefore there is acceleration present. Since there is a net force applied to the object, impulse is applied, therefore, there will be a change in momentum. The forces acting on the object are unbalanced

Question 29

Unbalanced force creates an __________, proportionate to the mass of the object

Answer 29

acceleration, F = ma

Question 30

What is the Impuse-Momentum Relation?

Answer 30

The effect of a force. The application of an impulse results in a change in momentum. Impulse is applied when force is applied over a period time. Change in momentum is the change in velocity of a mass. We assume that mass is constant.

Question 31

What is impulse?

Answer 31

Certain amount of force you apply for a certain amount of time to cause a change in momentum

Question 32

What is momentum?

Answer 32

Measure of the amount of motion in an object

Question 33

What is reaction forces?

Answer 33

Exerting a force will result in a reaction force.That is object A can exert a force on object B, if and only if, object B exerts a force on object A.

Question 34

What is “action-reaction”?

Answer 34

The force of B on A must be equal in magnitude, opposite in direction, and collinear to the force of A on B.