Chapter 3: Causes of Linear Motion

Question 1

Newton’s First Law and what it defines

Answer 1

First law: law of inertia
Resistance of an object to changing motion

Question 2

The following are examples of which one of Newton’s laws?:
-If no net external force acts on an object: that object will not move if it wasn’t moving to begin with
OR
-It will continue moving at constant speed in a straight line if it was already moving

Answer 2

1st Law: law of inertia

Question 3

Newton’s First Law: Interpretation
-If an object is at rest and the net external force acting on it is zero, the object must ____ at ____

Answer 3

remain at rest

Question 4

The product of an object’s mass and its linear velocity

Answer 4

Linear momentum

Question 5

Describe L=mv

Answer 5

Linear momentum (kg*m/s) = mass (kg) * v which is instantaneous velocity (m/s)

Question 6

True or false: Linear momentum quantifies current state of motion and resistance to change

Answer 6

True

Question 7

True or false: All forces between objects are internal forces

Answer 7

True

Question 8

If velocity of one object in the system increases, velocity of another object ____ to____momentum

Answer 8

decreases, conserve

Question 9

When two objects in a system collide head on AND separate
-system momentum is conserved

Answer 9

Elastic collisions

Question 10

When two objects in a system collide head on AND stay together moving at the same velocity

Answer 10

Inelastic

Question 11

True or false: Most real-life collisions are not perfectly elastic or inelastic

Answer 11

True

Question 12

What is a means of quantifying how elastic the collisions of an object are?
-ratio between the velocity of separation and the velocity of approach

Answer 12

The coefficient of restitution

Question 13

What is the difference between the postimpact velocities of two colliding objects called?

Answer 13

Velocity of separation

Question 14

What is the difference between the preimpact velocities of two colliding objects?

Answer 14

Velocity of approach

Question 15

Formula for coefficient of restitution

Answer 15

e=v1-v2/u1-u2
Where:
e= coefficient of restitution
v=post impact velocity of each object
u=preimpact of each velocity

Question 16

True or false: The coefficient of restitution is affected by materials and temperature of colliding objects

Answer 16

True

Question 17

For perfectly elastic collisions, what is the coefficient of restitution?

Answer 17

1.0

Question 18

For perfectly inelastic collisions, what is the coefficient of restitution?

Answer 18

0

Question 19

What is Newton’s Second Law

Answer 19

law of acceleration

Question 20

What will happen if a net external force is exerted on an object?

Answer 20

-The object will accelerate in the direction of the net external force
-its acceleration will be directly proportional to the net external force and inversely proportional to its mass

Question 21

Newton’s second law interpreted

Answer 21

-The average net force=mass of an object * the average acceleration of the object
m*a is a cause and effect relationship
-Forces cause acceleration
-Acceleration is the effect of forces

Question 22

True or false: If a net external force acts on an object, the object accelerates

Answer 22

True

Question 23

True or false: If an object accelerates, a net external force must be acting to cause the acceleration

Answer 23

True

Question 24

What is the product of average force and duration of force application?

Answer 24

Impulse

Question 25

____ causes change in ____of a body it acts on

Answer 25

Impulse, momentum

Question 26

Mass usually___,impulse changes____

Answer 26

Constant, velocity

Question 27

True or false: Impulse tells us that we can get the same change in momentum with a large force acting for a short time, or a small force acting for a long time

Answer 27

True
-This is why you should bend your knees when you land, why airbags work and why landing on a pillow hurts less than landing on concrete

Question 28

3 examples of impulse to increase momentum

Answer 28

Throwing, hitting and push-off
-technique involves increasing duration of force application in a specific direction

Question 29

3 examples of impulse to decrease momentum

Answer 29

Catching, landing, giving
-Safe performance involves increasing duration of force application to reduce the force magnitude ie landing mats, helmets and footwear

Question 30

Newton’s Third Law

Answer 30

Law of action-reaction

Question 31

What happens when an object exerts force on another object?

Answer 31

The other object exerts the same force on the first object but in the opposite direction

Question 32

True or false: You can think of the third law (law of action-reaction) as the law of equal and opposite

Answer 32

True

Question 33

Defining the law of action-reaction: for every action, there is and equal and ___ reaction.
There are ___bodies involved when force is exerted

Answer 33

opposite, two

Question 34

What is it called when the force on each body is the same size but in opposite directions

Answer 34

mirrored pairs

Question 35

Which law says that all bodies are attracted to one another with a force proportional to the product of their masses and inversely proportional to the square of the distance between them?
-ex: performance on earth (a large mass)

Answer 35

Law of universal gravitation

Question 36

Formula for Law of Universal Gravitation

Answer 36

F=G (m1+m2/r2)
Where:
F=force of gravity
G=gravitational constant
m1=mass of body 1 (object of analysis)
m2=mass of body 2 (mass of earth)
r= distance between the bodies (radius of earth)