# Pushy Astronaut

1. Apr 11, 2005

### Naeem

Pushy Astronaut

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a) An astronaut of mass 70 kg pushes off a satellite of mass 420 kg, exerting a force of 120 N for the 0.83 s they are in contact. What is the speed of the astronaut after they have separated?
vastronaut = m/s

HELP: Remember Newton's Third Law. The astronaut exerts a force on the satellite. What is the force that the satellite exerts on the astronaut?
HELP: Apply F = ma. You can figure out the force from the Third Law. You know the mass so you can find the acceleration. Once you know that, apply kinematics to find the speed.

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b) What is the speed of the satellite after they have separated?
vsatellite = m/s

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c) How far apart are they after 1 minute?
D= m

I request some intial help with these parts thanks,

2. Apr 11, 2005

### whozum

I know you know the basics of energy, thats all you need for these problems.

edit: not energy, momentum. im stupid.

Last edited: Apr 11, 2005
3. Apr 11, 2005

### Naeem

Impulse 'J' = Force * Delta t, Is this right

Impulse = Change in Momentum = mv-MV
so,

Given: Force = 120 N , delta t = 0.83 seconds.

m - mass of the astronaut = 70 kg
M - mass of the satellite = 420 kg

To find: Speed of the astronaut v_astronaut ( in m/s)

mv-MV = 120 * 0.83 = 99.6 Ns

Then what,,.......

4. Apr 11, 2005

### whozum

$$Ft = mv$$

F = 120, t = 0.83. The same force is applied to both the rocket and the ship. So then:

[itex] v = \frac{Ft}{m} [/tex] for each component.

5. Apr 16, 2005

### Naeem

Thanks, whozum, I finally got them all.!

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