PLease help on these 2 questions (momentum-impulse fans here)

  • Thread starter Dmt669
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In summary, by applying the principle of conservation of momentum, the final velocity of the astronaut in the first problem is 4 m/s in the opposite direction of their initial velocity. In the second problem, we can solve for the final velocity of the rock by setting the initial momentum of the astronaut and rock equal to the final momentum of the rock. This results in a final velocity of approximately 0.06 m/s for the rock.
  • #1
Dmt669
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0
Please help

An astronaut , 80 KG, is carrying a bag which is 20 KG, walking at a speed of 2 M/S toward a station, He throw the 20 KG bag forward at 6 M/s, what is his final velocity and direction(away from station, toward station)

heres another one

an astronaut is walking at .15 M/S toward a station, he wants to stop, he throws a 2.5 KG rock toward the station , what does a speed of the rock have to be in order for him to stop, thanks

:tongue: :tongue2: :biggrin: :rolleyes:
 
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  • #2
The total momentum is always conserved.
Before the astronaut throws the rock, the total momentum is:
[tex]p=(m_a+m_b)v[/tex]
where [itex]m_a[/itex] is the mass of the astronaut and [itex]m_b[/itex] the mass of the bag.
What is the total momentum after the astronaut has thrown the rock?

Same reasoning applies to the second question.
 
  • #3
Galileo,u mixed the bag with the rock and hence the problems :tongue2:

Now,after the precious indications given,which could have been put into 4 simple words "APPLY CONSERVATION OF MOMENTUM",what are the results...?

Daniel.
 
  • #4
Dmt669 said:
Please help

An astronaut , 80 KG, is carrying a bag which is 20 KG, walking at a speed of 2 M/S toward a station, He throw the 20 KG bag forward at 6 M/s, what is his final velocity and direction(away from station, toward station)

heres another one

an astronaut is walking at .15 M/S toward a station, he wants to stop, he throws a 2.5 KG rock toward the station , what does a speed of the rock have to be in order for him to stop, thanks

:tongue: :tongue2: :biggrin: :rolleyes:

Apply conservation of momentum, taking care to make sure the signs of the velocities are consistently applied. And show your thoughts and working first.
 
  • #5
Galileo said:
The total momentum is always conserved.
Before the astronaut throws the rock, the total momentum is:
[tex]p=(m_a+m_b)v[/tex]
where [itex]m_a[/itex] is the mass of the astronaut and [itex]m_b[/itex] the mass of the bag.
What is the total momentum after the astronaut has thrown the rock?

Same reasoning applies to the second question.

i am having trouble finding the final velocity of the astronaut though
 
  • #6
Dmt669 said:
i am having trouble finding the final velocity of the astronaut though

In the first problem, take the direction of travel toward the station as positive.

What is the initial momentum of the astronaut-bag combo ?

What is the final momentum of the bag ?

Therefore what is the final momentum of the astronaut ? Hence what is the final velocity of the astronaut ?

Do the second problem with the same basic principles.
 
  • #7
Curious3141 said:
In the first problem, take the direction of travel toward the station as positive.

What is the initial momentum of the astronaut-bag combo ?

What is the final momentum of the bag ?

Therefore what is the final momentum of the astronaut ? Hence what is the final velocity of the astronaut ?

Do the second problem with the same basic principles.

WHAT Formula should I use
 
  • #8
Dmt669 said:
WHAT Formula should I use

Do you mean to say that you don't know the definition of momentum ? You've never learned [itex]p = mv[/itex] ?
 
  • #9
is the answer to the first [roblem 4 m/s backwards
 
  • #10
Dmt669 said:
is the answer to the first [roblem 4 m/s backwards

That is not correct. Show the working please.
 

1. What is the difference between momentum and impulse?

Momentum is a measure of an object's motion, specifically its mass and velocity. It is a vector quantity, meaning it has both magnitude and direction. Impulse, on the other hand, is a force applied over a period of time, resulting in a change in an object's momentum. In other words, impulse is the change in an object's momentum.

2. How are momentum and impulse related?

Momentum and impulse are related by Newton's second law of motion, which states that force is equal to the change in momentum over time. This means that the greater the force applied to an object over a longer period of time, the greater the change in momentum.

3. How do you calculate momentum?

Momentum is calculated by multiplying an object's mass by its velocity. The equation for momentum is p = m * v, where p is momentum, m is mass, and v is velocity. Momentum is typically measured in kilograms-meters per second (kg*m/s).

4. How do you calculate impulse?

Impulse is calculated by multiplying force by time. The equation for impulse is J = F * t, where J is impulse, F is force, and t is time. Impulse is typically measured in Newton-seconds (N*s).

5. How do momentum and impulse relate to real-world situations?

Momentum and impulse are important concepts in understanding the effects of forces on objects in motion. In real-world situations, they can help us understand the outcomes of collisions, explosions, and other interactions between objects. They are also crucial in designing and engineering systems, such as car safety features, where minimizing the change in momentum can prevent serious injuries or damage.

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