Impulse Momentum Theorem and space probe

In summary, the first problem involves finding the momentum of a space probe after a retrorocket is fired to slow it down, using the impulse-momentum theorem. The second problem involves finding the height from which a student fell, using the conservation of energy principle and the initial velocity of the student obtained from impulse/momentum.
  • #1
shaka23h
38
0
Hi, I'm kinda lost on these 2 problems.

A space probe is traveling in outer space with a momentum that has a magnitude of 7.15 x 107 kg·m/s. A retrorocket is fired to slow down the probe. It applies a force to the probe that has a magnitude of 1.81 x 106 N and a direction opposite to the probe's motion. It fires for a period of 9.56 s. Determine the momentum of the probe after the retrorocket ceases to fire.

On this first question I have no idea if I'm going to have to find the mass and than use the impulse momentum theorem? If so how would I go about finding the mass for it?



A student (m = 65 kg) falls freely from rest and strikes the ground. During the collision with the ground, he comes to rest in a time of 0.017 s. The average force exerted on him by the ground is +15000 N. From what height did the student fall? Assume that the only force acting on him during the collision is that due to the ground.


On this problem I think I'm suppose to apply the constant acceleartion equation to it? But I have no idea how to find the t in this problem. I don't think the 0.017s is the T that I'm suppose use?


Any help would be greatly appreciate it
 
Physics news on Phys.org
  • #2
shaka23h said:
Hi, I'm kinda lost on these 2 problems.

A space probe is traveling in outer space with a momentum that has a magnitude of 7.15 x 107 kg·m/s. A retrorocket is fired to slow down the probe. It applies a force to the probe that has a magnitude of 1.81 x 106 N and a direction opposite to the probe's motion. It fires for a period of 9.56 s. Determine the momentum of the probe after the retrorocket ceases to fire.

On this first question I have no idea if I'm going to have to find the mass and than use the impulse momentum theorem? If so how would I go about finding the mass for it?
Do you really need to know that mass? What is the impulse equal to?


A student (m = 65 kg) falls freely from rest and strikes the ground. During the collision with the ground, he comes to rest in a time of 0.017 s. The average force exerted on him by the ground is +15000 N. From what height did the student fall? Assume that the only force acting on him during the collision is that due to the ground.


On this problem I think I'm suppose to apply the constant acceleartion equation to it? But I have no idea how to find the t in this problem. I don't think the 0.017s is the T that I'm suppose use?
Think about conservation of energy. What must the velocity be just before the impact? What's the kinetic energy at this point?
 
  • #3
Ok Mr. Advisor,

Thanks to your help I figured out what i was doing wrong on my first problem. I didn't take into consideration that the opposite direction accounts for a negative value. I know that Impulse = Change in momentum which is also equal to net force x change in time. After finding the impulse I added the initial momentum value to it and found my final momentum. :) thanks a lot.



I am still having trouble on number 2 because I don't know how to apply the conservation of energy principle to this problem because thi swas in the impulse-momentum chapter. I could not find a equation in this chapter that would allow me to find the distance of anything. Maybe I'm just stupid or just thinking it wrong. I'm thinking this problem as a free fall problem yet when I looked at that equation it didn't seem very logical either. :(
 
Last edited:
  • #4
shaka23h said:
Ok Mr. Advisor,

Thanks to your help I figured out what i was doing wrong on my first problem. I didn't take into consideration that the opposite direction accounts for a negative value. I know that Impulse = Change in momentum which is also equal to net force x change in time. After finding the impulse I added the initial momentum value to it and found my final momentum. :) thanks a lot.
Sounds good to me. There's no need for the Mr. Advisor (I'm not a teacher :cool: ), Hoot will do. And welcome to the Forums.
shaka23h said:
I am still having trouble on number 2 because I don't know how to apply the conservation of energy principle to this problem because thi swas in the impulse-momentum chapter. I could not find a equation in this chapter that would allow me to find the distance of anything. Maybe I'm just stupid or just thinking it wrong. I'm thinking this problem as a free fall problem yet when I looked at that equation it didn't seem very logical either. :(
Okay, firstly you can use impulse/momentum to find the velocity of the student just before the collision, yes? Now, with this information you can find the kinetic energy of the student just before the collision. As we are ignoring drag what can you say about the (gravitational) potential energy of the student before he/she fell?
 

Related to Impulse Momentum Theorem and space probe

1. What is the Impulse Momentum Theorem and how is it related to space probes?

The Impulse Momentum Theorem is a fundamental law in physics that states that the change in momentum of an object is equal to the impulse applied to it. In the context of space probes, this theorem is used to calculate the change in momentum of the probe as it travels through space due to various forces acting on it, such as gravity and thruster propulsion.

2. How is the Impulse Momentum Theorem used in the design and navigation of space probes?

The Impulse Momentum Theorem is used in the design and navigation of space probes in several ways. Firstly, it helps engineers calculate the amount of thrust needed for the probe to reach its desired destination. Secondly, it is used to determine the necessary velocity changes for the probe to enter orbit around a planet or moon. Finally, it is used to adjust the trajectory of the probe during its journey to ensure it stays on course.

3. How does the Impulse Momentum Theorem contribute to the success of space missions?

The Impulse Momentum Theorem is crucial for the success of space missions as it helps engineers and scientists accurately plan and execute the trajectory of a space probe. By understanding the forces acting on the probe and using the theorem to calculate its change in momentum, the probe can be navigated with precision and achieve its mission objectives.

4. What are some challenges in applying the Impulse Momentum Theorem to space probes?

One of the main challenges in applying the Impulse Momentum Theorem to space probes is the complex and dynamic nature of space. There are various forces at play, such as the gravitational pull of different objects, solar wind, and radiation, which can all affect the momentum of a space probe. Additionally, the extreme distances involved in space travel make it difficult to accurately predict and account for all these factors.

5. Are there any limitations to the Impulse Momentum Theorem for space probes?

While the Impulse Momentum Theorem is a useful tool for designing and navigating space probes, it does have some limitations. For example, it assumes that the forces acting on the probe are constant and linear, which may not always be the case in the unpredictable environment of space. Additionally, the theorem does not account for the effects of relativity, which can become significant at high speeds and large distances.

Similar threads

Replies
1
Views
825
  • Introductory Physics Homework Help
Replies
7
Views
1K
  • Introductory Physics Homework Help
Replies
13
Views
6K
  • Introductory Physics Homework Help
Replies
11
Views
3K
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
3K
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
4
Views
5K
  • Introductory Physics Homework Help
Replies
2
Views
2K
Back
Top