Question

Help

Answer 1

B

Answer 2

@Vocaloid

Answer 3

good!

Answer 4

you're given big G, the two masses, and d, find the force

Answer 5

C

Answer 6

actually A

Answer 7

yeah, I got A as well, gj

Answer 8

A

Answer 9

yeah that's correct ^^ forgottoaddthevalueofbigG

Answer 10

POint d

Answer 11

ok, so the velocity is the highest at the perigree so the point that's closest to the central body (the sun in this case)

Answer 12

so which point would it be?

Answer 13

The gravity of the Sun keeps the planets in their orbits. They stay in their orbits because there is no other force in the Solar System which can stop them.

Answer 14

Point c

Answer 15

Sorry I fell asleep

Answer 16

well done ^^

Answer 17

A

Answer 18

you might be mixing these two terms up

Answer 19

Yeah I def was, so it should be C then?

Answer 20

good ^_^ C

Answer 21

any guesses? there's only one that's an actual physical object, the rest are concepts

Answer 22

D

Answer 23

good ^^

Answer 24

Point A because that is the farthest from the sun?

Answer 25

\(\color{#0cbb34}{\text{Originally Posted by}}\) @Vocaloid
Created with RaphaëlReply Using Drawing

ok, so the velocity is the highest at the perigree so the point that's closest to the central body (the sun in this case)
\(\color{#0cbb34}{\text{End of Quote}}\)

Answer 26

good, point A

Answer 27

F = m1 * m2 * G /r^2, solve for r

Answer 28

F=2 * 5 * 7.41

Answer 29

G = (6.67×10^−11)

Answer 30

F=2 * 5 * (6.67×10^−11)

Answer 31

good but don't forget the r^2 in the denominator

Answer 32

F=2 * 5 * (6.67×10^−11)/r^2

Answer 33

yeah, that's it.

you're also given the force (7.41e-11) so plug this in and solve for r

Answer 34

7.41e-11=2 * 5 * (6.67×10^−11)/r^2

Answer 35

good, now solve for r

Answer 36

remember that 7.41e-11 means 7.41*10^-11

Answer 37

D

Answer 38

good, that's what i got too

Answer 39

A

Answer 40

awesome

Answer 41

What is the momentum of a tiger that has a mass of 81 kg and runs with a velocity of 5.4 m/s to the east?

Answer 42

momentum = p = mv

Answer 43

so just 81*5.4=437.4

Answer 44

so just 81*5.4=437.4

Answer 45

good, but since momentum is a vector it's 437.4 kg * m/s east

[remember these units for momentum]

Answer 46

(if you ever forget it's just the units of velocity and the units of mass multiplied, so kg * m/s)

Answer 47

A horse has a momentum of 1200 kg·m/s. If the horse has a mass of 313 kg, what is the speed of the horse?

Answer 48

p = mv, this time solve for v

Answer 49

1200=313(v)
v=3.83 m/s

Answer 50

good, since it's speed not velocity, no direction needed here

Answer 51

A car has a speed of 23 m/s and a momentum of 31,050 kg·m/s. What is the mass of the car

p=mv
31,050=23(m)
m=1350kg

Answer 52

good

Answer 53

A boat uses its motor to increase its speed from 5 m/s to 7 m/s. If the boat has a mass of 250 kg, what was the impulse applied by the motor?

Answer 54

impulse = change in momentum = m*deltav

Answer 55

250*5
250*7

Answer 56

good, then just subtract 250*7 - 250*5

Answer 57

250*5=1250
250*7=1750

1750-1250=500

Answer 58

good

units of impulse are the same as momentum, kg * m/s

Answer 59

Dave is moving 3 m/s when he crashes his bike into a wall, which stops him in 0.6 seconds. If Dave and his bike have a mass of 90 kg, what was the force applied by the wall

Answer 60

Would this be the same formula ?

Answer 61

almost, we just have to use the full form

Answer 62

(last row)

F * delta t = m * delta v

you're given everything except F, so solve for F

Answer 63

F (0.6) = 90 * 3
F=450

Answer 64

F=450N

Answer 65

yup, well done

Answer 66

Dale (m = 75 kg) skis across a horizontal surface at a velocity of 5 m/s to the west. He drags his ski poles, which gives him an impulse of 300 kg·m/s to the east. What is his new velocity?

Answer 67

For this one I would suggest writing delta v as (vf - vi) since we want the new velocity

so impulse = m(vf - vi)

solve for vf

Answer 68

impulse = m(vf - vi)
300=75(vf-5)
vf=9

Answer 69

hm

Answer 70

hold on I think we need to re-do the calculation, I just realized the impulse is in the opposite direction as the initial velocity

Answer 71

Yeah I just did the math too and it doesn't work out

Answer 72

I think it needs to be -300 = 75(vf-vi)

Answer 73

does that work out ? I'm getting something different

Answer 74

I end up w/ 1 m/s west

Answer 75

-300 = 74(vf-5), vf = 1 and since it's still positive we're going west

Answer 76

the mass is 75 isn't it ?

Answer 77

** yeah I meant to say 75

Answer 78

Matt (m = 80 kg) and Trey (m = 90 kg) slide across an ice skating rink and collide with each other. Before the collision, Matt was moving 3 m/s to the east and Trey was moving 2 m/s to the west. After the collision, Matt is moving 1.5 m/s to the west.

a. What was the total momentum of the system before the collision?


b. What is the total momentum of the system after the collision?


c. What is Trey's speed after the collision?

Answer 79

well for a it would be p=mv

Answer 80

would i just calculate the momentum for both and add them?

Answer 81

good, so you would sum the momenta for both Matt and Terry [keep in mind they're going in opposite directions so the final momenta will be smaller than either of the original momentum]

Answer 82

Matt:
p=mv
p=80*3
p=240 kg * m/s

Trey:
p=mv
p=90*2
p=180 kg * m/s

240+180=420 kg * m/s

Answer 83

This for a

Answer 84

you're very close, however, we must take direction into account

Matt is going east, let's define east as the positive x and west as negative x

240-180=60 kg * m/s east

Answer 85

Oh so just subtract because its opposite

Answer 86

ANd i added where i was wrong

Answer 87

good

for b) it's the same as a) 60 kg * m/s east b/c momentum is conserved

Answer 88

for c) use the final momentum to calculate Trey's velocity

60 = (80)(-1.5) + (90)v solve for v

Answer 89

v=-2

Answer 90

2

Answer 91

SOrry

Answer 92

good so Trey's going 2 m/s east

Answer 93

can we open a new question this one is starting to lag a bit

Answer 94

SUre