Newton's 3rd law and spacewalking

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In summary, the problem involves an 80.0 kg astronaut pushing off a 620kg satellite with a force of 100N over a duration of 0.590s. To find the distance between them after 1.20min, the kinematics equation xf=xi+vi(t)+0.5at^2 is used for both objects. The astronaut has an acceleration of 1.25m/s^2 and the satellite has an acceleration of 0.1613 m/s^2. However, the objects are only accelerating during the 0.59s that the force is applied, so the equation F(delta t) =m(delta v) is used to find their velocities. The velocities are then added and multiplied
  • #1
sunbunny
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I'm having troubles with this problem:

An 80.0 kg spacewalking astronaut pushes off a 620kg satellite, exerting a 100N force for the 0.590s it takes him to straighten his arms.How far apart are the astronaut and the satellite after 1.20min ?

I know that i need to somehow set it up to be a kinematics problem and that i need to find the acceleration and how fast the astronaut and the satellite are moving.

I tried to use F=ma where a=100N/80kg and then the same for the orbital

for the astronaut i got the acceleration to equal 1.25m/s^2
for the satellite a=0.1613 m/s^2
and the change in time used was 72-0.59s=71.41s

I then put these into xf=xi +vi(t)+.5at^2 to find the distances

I then added their distances together to get the total distance between them however this way that I did it was wrong.

I got 3187.1m (astronaut) +411(orbit)

any feedbaclk would be great
 
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  • #2
sunbunny said:
I'm having troubles with this problem:

An 80.0 kg spacewalking astronaut pushes off a 620kg satellite, exerting a 100N force for the 0.590s it takes him to straighten his arms.How far apart are the astronaut and the satellite after 1.20min ?

I know that i need to somehow set it up to be a kinematics problem and that i need to find the acceleration and how fast the astronaut and the satellite are moving.

I tried to use F=ma where a=100N/80kg and then the same for the orbital

for the astronaut i got the acceleration to equal 1.25m/s^2
for the satellite a=0.1613 m/s^2
and the change in time used was 72-0.59s=71.41s

I then put these into xf=xi +vi(t)+.5at^2 to find the distances

I then added their distances together to get the total distance between them however this way that I did it was wrong.

I got 3187.1m (astronaut) +411(orbit)

any feedbaclk would be great
The astronaut and satellite are accelerating only when the force is applied over the 0.59 second period. After that, once contact is gone, they both must move at constant velocity, per Newton's first law.
 
  • #3
Okay, thank you.

So if they are only accelerating during the 0.59s how would i go about finding the acceleration for them during this time interval?

I was using F=ma but this formula doesn't have time in it. How would you suggest that I go about this?
 
  • #4
sunbunny said:
Okay, thank you.

So if they are only accelerating during the 0.59s how would i go about finding the acceleration for them during this time interval?

I was using F=ma but this formula doesn't have time in it. How would you suggest that I go about this?
Use F(delta t) =m(delta v)=m(v_f -v_i). That's the same as F=ma.
 
  • #5
Thank you so much!from the equation you gave me, i found the velocity of the astronaut to be 0.7373m/s and the satellite to be 0.095167m/s. from there, i put these velocities into:

xf=vi(delta t) and then I added the two distances and got the answer
59.5m. Thanks a a lot I really appreciated it!
 
  • #6
hi i have a similar question to this and when i tried to recreate your workings it wasnt working for me can u please explain to me what you did..thanks :))
 
  • #7
brunettegurl said:
hi i have a similar question to this and when i tried to recreate your workings it wasnt working for me can u please explain to me what you did..thanks :))

Consider the force applied and the duration.

Applying the force to each mass results in a change in momentum - which gives you the speed of each.

The speeds are in opposite directions so simply add the speeds and determine the distance given the time.
 
  • #8
so wld i be using the Fdeltat = mdeltav for each of the objects...using this velocity and the second time given in the question figure out the distance and add them together??
 
  • #9
brunettegurl said:
so wld i be using the Fdeltat = mdeltav for each of the objects...using this velocity and the second time given in the question figure out the distance and add them together??

Basically yes.

Though I think of it more as determining their relative velocity first from the F*Δt on each and then applying the duration of their drift. (The magnitudes of the velocities add since they are in opposite directions,)
 
  • #10
we assume for each object that the vintial is zero right?? so then wld the distance we get be a negative or a positive value??
 

Related to Newton's 3rd law and spacewalking

1. What is Newton's 3rd law and how does it apply to spacewalking?

Newton's 3rd law states that for every action, there is an equal and opposite reaction. In the context of spacewalking, this means that when an astronaut pushes against the surface of their spacecraft or another object, the object will push back with an equal force. This allows astronauts to move and maneuver in space.

2. How does Newton's 3rd law impact the movement of objects in space during a spacewalk?

During a spacewalk, the application of Newton's 3rd law is crucial for astronauts to move and control their movements. By pushing against the spacecraft or other objects, astronauts can propel themselves in the opposite direction and change their position or trajectory. This law also applies to tools and equipment used during a spacewalk, as they can be used to push against objects and move them.

3. Can Newton's 3rd law be observed in space from Earth?

Yes, Newton's 3rd law can be observed in space from Earth. For example, when a spacecraft launches into orbit, the force of the engines pushing against the ground causes an equal and opposite force that propels the spacecraft into the air. This law is also evident in the movement of astronauts outside the spacecraft during a spacewalk.

4. Are there any exceptions to Newton's 3rd law in spacewalking?

While Newton's 3rd law generally applies to the movement of objects in space, there are some exceptions. For example, in microgravity environments, the forces may not be exactly equal and opposite due to the lack of gravity. Additionally, there may be other external forces at play, such as air resistance, that can impact the movement of objects in space.

5. How does understanding Newton's 3rd law benefit spacewalking missions?

Understanding Newton's 3rd law is crucial for the success of spacewalking missions. By applying this law, astronauts are able to control their movements and navigate in space. It also allows for the safe and efficient use of tools and equipment during a spacewalk. Without understanding this law, astronauts would have a much more difficult time performing tasks and moving around in space.

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