Ch. 4 Sec. 6&7

Question 0

When an object is at rest what doesn’t it have?

Answer 0

• no acceleration

- no net force acting on it

Question 1

What is an object at rest?

Answer 1

Sum of the forces on the object

Question 2

When an object is moving at a constant speed what doesn’t it have?

Answer 2

No net force on it

Question 3

What does the first law of motion not have?

Answer 3

No net force on it.

Question 4

In the second law of motion what doesn’t it have?

Answer 4

No acceleration = no force

Question 5

Are objects moving up or down at a constant speed the same or different?

Answer 5

Same

Question 6

When roller coasters move up, what else moves up?

Answer 6

The acceleration moves up

Question 7

What does Newton’s 2nd law show?

Answer 7

For acceleration going up the net force has to push up

Question 8

What is air resistance?

Answer 8

The air applies a force to materials that oppose the force of gravity

Question 9

What is apparent weight?

Answer 9

The net force acting on you by a surface in the direction toward earth.

Question 10

If you accelerate upward what happens?

Answer 10

If you accelerate upward then your apparent weight is greater than your unaccelerated weight, because there is a greater force between you and the surface.

Question 11

If you are traveling at a constant speed, what happens?

Answer 11

If you are traveling at a constant speed, your apparent weight is equal to your accelerated weight.

Question 12

What is the equation for the centripetal force?

Answer 12

Fc=mv^2/r

Question 13

What is the equation for centripetal acceleration?

Answer 13

ac=v^2/r

Question 14

For an object traveling in a circular path at a constant speed what happens?

Answer 14

For an object traveling in a circular path at a constant speed, the centripetal acceleration and centripetal force are always perpendicular to the objects velocity.

Question 15

What happens to roller coasters?

Answer 15

Roller coasters curve where the car tilts vertically and the wheels face outside of the circle the force is toward the center is normal force of the track on the wheels.

Question 16

Are roller coasters parallel or perpendicular to the track?

Answer 16

Perpendicular

Question 17

What is normal force?

Answer 17

Normal force is a constant force exerted on an object by the surface it is in contact with and it points perpendicular to the surface toward the object.

Question 18

What is Fg at top do?

Answer 18

Acts down toward the center

Question 19

What is Fz?

Answer 19

Weight-top and bottom are the same length since the car is the same weight

Question 20

What is FN at the top?

Answer 20

It is smaller since the weight contributes = if speed is down the Fc is down

Question 21

What is Fc?

Answer 21

Different lengths from top to bottom since there is larger speed at bottom of loop

Question 22

What is the force on you in a car?

Answer 22

On a level track… The sum of forces is 0

Question 23

What happens at the bottom of the loop?

Answer 23

The net force is toward center to keep moving in a circular motion

Question 24

What happens at the top of the loop?

Answer 24

The net force is downward toward the center

Question 25

What do astronauts do?

Answer 25

Astronauts test themselves to see how many g’s they can stand.

Question 26

What does one g stand for?

Answer 26

9.8 m/s^2

Question 27

What does roller coaster safety require?

Answer 27

Roller coaster safety requires 4g’s for entire ride