Test Review Chapters 12-16 Relativity. Question #1 What happens to the gravitational force when 2...

Test ReviewTest ReviewChapters 12-16Chapters 12-16

RelativityRelativity

Question #1Question #1

What happens to the What happens to the gravitational force when 2 gravitational force when 2 objects get farther away objects get farther away

from each other?from each other?

221

d

mGmF

It decreases!It decreases!

Question #2Question #2

A 35 kg rock and a 250 kg rock A 35 kg rock and a 250 kg rock are placed 17 m apart. What are placed 17 m apart. What

is the gravitational force is the gravitational force between them?between them?

221

d

mGmF

NxF

xF

9

2

11

100.2

17

)250)(35)(1067.6(

Question #3Question #3

How fast must a How fast must a spaceship travel to spaceship travel to

be able to leave be able to leave the earth’s the earth’s

gravitational pull?gravitational pull?

8 km/s8 km/s

Question #4Question #4

How long does it take How long does it take light from the sun to light from the sun to

travel to Earth?travel to Earth?

8 minutes8 minutes

Question #5Question #5

How much energy is How much energy is contained within a T-84 contained within a T-84 calculator with a mass calculator with a mass

of 0.89 kg?of 0.89 kg?

JxE

xE

xE

mcE

16

16

28

2

100.8

)1000.9)(89(.

)1000.3)(89(.

Question #6Question #6

The sun exerts a 3.5 x 10The sun exerts a 3.5 x 102222 N force N force on the earth. on the earth.

What is the What is the distancedistance between the between the 1.99 x 101.99 x 103030 kg sun and the kg sun and the

5.97 x 105.97 x 102424 kg Earth? kg Earth?

221

d

mGmF

mxd

xd

x

xxxd

xxxdx

d

xxxx

11

222

22

2430112

243011222

2

24301122

105.1

1026.2

105.3

)1097.5)(1099.1)(1067.6(

)1097.5)(1099.1)(1067.6(105.3

)1097.5)(1099.1)(1067.6(105.3

Question 7Question 7In Feb. 2007, the Hubble Telescope In Feb. 2007, the Hubble Telescope captured pictures of a dying star with captured pictures of a dying star with

a mass of 2.0 x 10a mass of 2.0 x 103030 kg.. kg..

If this star was 4,200 light years away, If this star was 4,200 light years away, how long ago did the star die?how long ago did the star die?

~ 4,200 years ago~ 4,200 years ago

Question #8Question #8

At what point during the planet’s At what point during the planet’s orbit around the sun does it have orbit around the sun does it have

the the leastleast amount of velocity? amount of velocity?

SS

Question #9Question #9

What is the What is the speed of light?speed of light?

(in m/s)(in m/s)?

3.00 x 103.00 x 108 8 m/sm/s

Question #10Question #10

What is the gravitational force What is the gravitational force between a 7.5 x 10between a 7.5 x 1055 kg object kg object

and a 2.50 x 10and a 2.50 x 1088 kg object kg object that are 2.5 x 10that are 2.5 x 101111 m apart? m apart?

221

d

mGmF

NxF

x

xxxF

19

211

8511

100.2

)105.2(

)1050.2)(105.7)(1067.6(

Question #11Question #11

2 objects are attracted to 2 objects are attracted to each other. each other.

What happens to their speed What happens to their speed as they get closer?as they get closer?

It increases!It increases!

Question #12Question #12

What were black holes What were black holes before they became before they became

black holes?black holes?

Stars!Stars!

Question #13Question #13

Name 2 points during the planet’s Name 2 points during the planet’s orbit around the sun where it has orbit around the sun where it has

the the samesame amount of velocity. amount of velocity.

All below are correct…All below are correct…

P & VP & V

Q & UQ & U

R & TR & T

Question #14Question #14

If our sun were to become a If our sun were to become a black hole tomorrow, what black hole tomorrow, what

would happen to the earth’s would happen to the earth’s orbit around the sun?orbit around the sun?

Nothing.Nothing.

……because our orbit is due to the gravitation because our orbit is due to the gravitation between the sun & the earth, and that between the sun & the earth, and that didn’t change simply because the sun didn’t change simply because the sun became a black hole. became a black hole.

A black hole is the same mass, but in a A black hole is the same mass, but in a much smaller package!much smaller package!

The end.The end.