CH 4-5-6

Question 1

What weighs 1 N?

Answer 1

an apple

Question 2

What weighs 10N?

Answer 2

Large Textbook (a 1 liter bottle of soda)

Question 3

What weighs 100N?

Answer 3

3 Gallons of milk

Question 4

What weighs 1000N?

Answer 4

Mr. Nystrom wearing a backpack full of books

Question 5

If you weigh 600N and are hanging on a rope, you are pulling down 600N on the rope. The rope is pulling ______

Answer 5

up 600N on you!

Question 6

If you weigh 600N and jump off of a building, do you accelerate towards the earth? Does the earth accelerate towards you?

Answer 6

YES, you accelerate toward the earth and YES the earth accelerates toward you (it is hard to see)

Question 7

How can you think of gravity to help you “see” objects being pulled towards eachother?

Answer 7

Imagine a bungee between them. A bungee between two cars may pull them both together at the same acceleration, but a bungee between a car and a skateboard will mostly pull the skateboard more. MASS RESISTS ACCELERATION

Question 8

Why don’t you see the earth move when you jump up?

Answer 8

It is so massive that it barely moves

Question 9

If force = mass * acceleration, then acceleration =

Answer 9

FORCE / MASS

Question 10

if force = mass * acceleration, then mass=

Answer 10

FORCE / ACCELERATION

Question 11

When you fire a gun, the force on the bullet is equal to the _____________

Answer 11

force on the gun

Question 12

why does a bullet go faster forward than the gun moves backwards if they have the same force?

Answer 12

the gun has more mass. If you push a roller skate with the same force that you push a bus, the rollerskate will accelerate faster! Mass resists acceleration.

Question 13

What is a way to think of mass when it comes to movement?

Answer 13

MASS RESISTS ACCELERATION (this is what we call inertia)

Question 14

How do you sketch the resultant force of two vectors?

Answer 14

USE THE PARALELLOGRAM RULE.

Question 15

What does the delta (the little triangle) symbol mean?

Answer 15

It means “CHANGE IN”

Question 16

What is Newton’s First Law?

Answer 16

Object stays at rest, or moves at a constant velocity in a straight line unless a force acts on it.

Question 17

What is Newton’s Second Law?

Answer 17

F= ma Force increases acceleration, mass resists accelertion

Question 18

What is Newton’s Third Law?

Answer 18

Every action (force) has an equal and opposite reaction

Question 19

Give a quick summary of Newton’s three laws of motion:

Answer 19

FIRST: objects in motion or rest stay that way, SECOND: harder to push more massive objects , THIRD: action have equal opposite reactions

Question 20

What are the three equations from newton’s second law? (my fish is from massachusetts)

Answer 20

a=F/m F= ma F/a = m

Question 21

If you are given a force and an acceleration, you can find ____ by using the equation ____

Answer 21

mass, m= F/a

Question 22

If you are given a mass and an acceleration, you can find ____ by using the equation ____

Answer 22

Force, F= ma

Question 23

If you are given a force and a mass, you can find ____ by using the equation ____

Answer 23

a = F/m

Question 24

Describe what NET force is

Answer 24

It is what is left after you combine all the forces (things cancel out).

Question 25

How can we add two vectors (find resultant) by sketching?

Answer 25

Use the parallelogram rule, and the DIAGONAL is the resultant vector when both components start from the same spot.

Question 26

How do we make sure our calculator is in the right mode?

Answer 26

press MODE> put cursor on DEGREES> press ENTER

Question 27

What is the net force on an object at rest?

Answer 27

zero (not accelerating), but has potential energy!

Question 28

What is the net force on an object moving at a constant velocity? Why?

Answer 28

zero (not accelerating) but has kinetic energy!

Question 29

What has to be happening in order for net force to not be zero?

Answer 29

it must be ACCELERATING (changing velocity). just moving is not enough, it has to be changing speeds!

Question 30

block on inclined plane: What is Fd and FN?

Answer 30

Fd is directional force DIAGONAL down plane along the slope, FN is normal force directly into the plane

Question 31

Explain what Fd is in plain terms

Answer 31

Directional force, it is the force that acts on the block pushing it down the ramp. it goes diagonally down the ramp, parallel to the ramp.

Question 32

Explain Fn in plain terms

Answer 32

It is the squeeze force between the block and the ramp. It measures the force going directly perpendicular into the plane. It is in the direction of an upside down thumb tack.

Question 33

How can remember the direction of the normal force?

Answer 33

a thumb tack on its back. the pointy side is in the direction of the normal force.

Question 34

Directional force (down along the plane) is:

Answer 34

Fd | It is directional, or down the plane, parallel to the plane, along the plane

Question 35

The force between the block and the ramp is

Answer 35

the normal force, Fn (the squeeze force)

Question 36

If you have weight, how do you find normal force?

Answer 36

w*cos (angle) gives normal force. "COS it's normal"

Question 37

If you have weight, how do you find directional force?

Answer 37

w*sin(angle) gives the directional force. "SINES GIVE DIRECTIONS"

Question 38

What do we use normal force to calculate?

Answer 38

FRICTION. it is the squeeze force since it is the measure of the force between the block and the plane, it determines amount of friction. Friction=FN * Mu

Question 39

The force of friction always acts____

Answer 39

in the opposide direction of motion

Question 40

You can calculate the force of friction by multplying ____ by ____

Answer 40

normal force by coefficient of friction

Question 41

Coefficients of friction are _____ for surfaces that are smooth and ____ for surfaces that are rough, or sticky.

Answer 41

smaller, larger

Question 42

What is the unit of force we use?

Answer 42

NEWTON

Question 43

What is the unit of weight we use?

Answer 43

NEWTON

Question 44

what is a NEWTON a unit for?

Answer 44

for FORCE and WEIGHT (weight is a force)

Question 45

What are the units in a NEWTON?

Answer 45

kg*m/s2 (notice it it a mass * acceleration)

Question 46

what are the units we use for acceleration?

Answer 46

m/s2

Question 47

What are the units we use for mass?

Answer 47

kg

Question 48

a newton (F) divided by acceleration (a) (m/s2) will give you

Answer 48

mass (kg)

Question 49

a newton (F) divided by a mass (m) (kg) will give you

Answer 49

an acceleration (m/s2)

Question 50

a mass (m)(kg) multiplied by an acceleration(a) (m/s2) will give you

Answer 50

a newton (force)

Question 51

is mass a force? explain

Answer 51

No. to be a force you need a mass AND acceleration. Mass is a scalar quantity and has no direction. Force is a vector.

Question 52

is weight a force? explain

Answer 52

YES. F=ma, W=mg. gravity is an acceleration, so when you do mass times gravity, that is the same as mass times acceleration.

Question 53

How much does a 3kg object weigh?

Answer 53

about 30N

Question 54

Is acceleration scalar or vector?

Answer 54

vector (has direction and magnitude)

Question 55

What is the mass of a 35N object?

Answer 55

3.5 kg

Question 56

What is acceleration when 12N is applied to 3kg object? Why?

Answer 56

4 m/s2. Since F=ma, then a=F/m so 12N/3kg = 4m/s2

Question 57

What is the net force on a 10kg object that is accelerating at 2 m/s2

Answer 57

F = ma so 10(2) = 20N

Question 58

What is the mass of an object that acceleraties 5 m/s2 when a 30N force is applied?

Answer 58

m= F/a so 30/ 5 = 6kg

Question 59

What force do you need to accelerate a 1000kg car 5 m/s2 ? (ignore friction)

Answer 59

5000N

Question 60

What will the acceleration be of an 800kg car that is pushed with a force of 8000N? (ignore friction)

Answer 60

10m/s2

Question 61

What is terminal velocity?

Answer 61

the highest speed a falling object will reach because of air resistance

Question 62

What is the net force on an object that is moving at its terminal velocity? Explain

Answer 62

zero. it is not accelerating

Question 63

What receives a greater force of air resistance, an elephant or a feather falling? Why?

Answer 63

elephant. it is pushing through more air

Question 64

What is the difference between mass and weight?

Answer 64

mass is the amount of stuff, mass is a measure of resistance to change, weight is the force due to gravity on the planet it is on

Question 65

Which is more stable, mass or weight? Explain

Answer 65

mass is same on earth or moon, weight changes on different planets with diff gravity. Also, you weigh less on a plane than on the ground (gravity decreases the further from earth you are)

Question 66

Give an example of Newton's first law in real life:

Answer 66

an apple on a desk. net force is zero, until you push it off (things at rest or motion stay that way)

Question 67

Give an example of Newton's second law in real life:

Answer 67

harder to push a car than to push a skate board (mass resists acceleration, f=ma)

Question 68

Give an example of Newton's third law in real life:

Answer 68

the floor is pushing up on you as much as you are pushing down on the floor (equal and opposite)

Question 69

Do you weigh more on the ground or in an airplane?

Answer 69

On the ground. The further from an object, the less its gravitational pull influences you.

Question 70

An object in equilibrium is

Answer 70

standing still or moving at a constant velocity.

Question 71

if there is a net force then the object must be

Answer 71

accelerating.

Question 72

if an object is moving, must there be a force on it?

Answer 72

NO. it can be moving at a constant velocity with no force, if it's velocity changes, then there must be a force present.

Question 73

A 60N object has a _________

Answer 73

mass of 6kg

Question 74

A 55kg object has a _______

Answer 74

weight of 550N

Question 75

2.5N= ___kg

Answer 75

.25kg

Question 76

2.5kg=___N

Answer 76

25N

Question 77

if a force acts in the same direction as the velocity, then the object will

Answer 77

speed up (positive acceleration)

Question 78

if a force acts in the opposite direction as the velocity then the object will

Answer 78

slow down (negative acceleration, or deceleration)

Question 79

what is terminal velocity?

Answer 79

when the force of air resistance is equal to the weight ( weight is the force due to gravity). It is in equilibrium.

Question 80

what happens when an object reaches terminal velocity?

Answer 80

It stops accelerating. It has reached its top speed and it just continues down at a constant velocity.

Question 81

What is the net force of an object moving at its terminal velocity?

Answer 81

zero. No acceleration.

Question 82

If something is slowing down, then it is accelerating in the ________ direction

Answer 82

opposite.

Question 83

If something is speeding up, then it is accelerating in the ____ direction,

Answer 83

same

Question 84

if a problem says "constant velocity" that means that the acceleration is ____ and the net force is _____

Answer 84

the acceleration is zero and the net force is zero.