Having trouble starting gravity problem.

  • Thread starter Crusaderking1
  • Start date
  • Tags
    Gravity
In summary, the conversation discusses calculating the Earth's gravity force on a 70 kg astronaut who is repairing the Hubble Space Telescope 600 km above the Earth's surface, and comparing it to the astronaut's weight on the ground. The formula w=GmEm/RE^2 is mentioned, but the speaker is unsure how to use it. They are then advised to use the formula g = 9.8 x [R/(R+h)]^2 to find the gravity force, and then use the equation W=mg to determine the weight at the given altitude. The conversation ends with the speaker realizing their mistake and thanking the other person for their help.
  • #1
Crusaderking1
159
0

Homework Statement



A. Calculate the Earth's gravity force on a 70 kg astronaut who is repairing the Hubble Space Telescope 600 km above the Earth's surface

B. Compare this gravity force with his weight at the Earth's surface. (F/w)

Homework Equations



No idea

w=GmEm/RE^2 is just for the weight, but I don't know how to find part 1, which is needed for part 2.

The Attempt at a Solution



I don't know what formulas to use to answer these questions. Thanks.
 
Last edited:
Physics news on Phys.org
  • #2
What's a 70 km astronaut look like?

If you can calculate the weight of the astronaut at an altitude of 600 km, then you should easily be able to determine the weight of the same astronaut on the ground.
 
  • #3
Is the problem here just knowing how to interpret the formula you have, like you don't know what all of the variables mean and where to plug stuff in?
 
  • #4
SteamKing said:
What's a 70 km astronaut look like?

If you can calculate the weight of the astronaut at an altitude of 600 km, then you should easily be able to determine the weight of the same astronaut on the ground.
At height h, g = 9.8 x [R/(R+h)]^2
So find g, then use W=mg. The weight, W, is the gravity force.

problem is I get 9.80 m/s^2 here! So then the weight on the ground is the same.

This makes no sense.

9.8 * [6.38*10^6/(6.38*10^6+600)]^2 = 9.80 m/s^2 at the distance of 600 km.

so weight is 686 N, but so is it at Earth. What am I doing wrong?
 
Last edited:
  • #5
Villyer said:
Is the problem here just knowing how to interpret the formula you have, like you don't know what all of the variables mean and where to plug stuff in?

Probably, I keep messing the formula I found up miserably.
 
  • #6
In the radius at the bottom, you added 600. 600 is kilometers, 6.38*10^6 is meters.

Nevermind about the second point I had here a second ago, I was thinking of a different equation.
 
  • #7
Villyer said:
In the radius at the bottom, you added 600. 600 is kilometers, 6.38*10^6 is meters.

Nevermind about the second point I had here a second ago, I was thinking of a different equation.

Thanks for your help! much appreciated.
 
Last edited:

FAQ: Having trouble starting gravity problem.

1. What is gravity and why is it important to understand in problem solving?

Gravity is the force of attraction between two objects with mass. It is an important concept in problem solving because it affects the motion and interactions of objects in our daily lives. Understanding gravity allows us to make accurate predictions and calculations in various scientific fields, such as physics and astronomy.

2. Why do I have trouble starting gravity problems?

Starting gravity problems can be challenging because it involves understanding the concept of gravity, as well as applying various mathematical formulas and equations to solve the problem. It also requires a strong foundation in mathematics and problem solving skills.

3. How can I improve my understanding of gravity to solve problems more easily?

To improve your understanding of gravity, you can start by reviewing the fundamental principles of gravity, such as Newton's Law of Universal Gravitation. You can also practice solving different types of gravity problems, and seek help from teachers or peers if needed. Additionally, using visual aids, such as diagrams or graphs, can also aid in understanding and solving gravity problems.

4. What are some common mistakes people make when solving gravity problems?

Some common mistakes in solving gravity problems include using incorrect formulas, not considering all the forces acting on an object, and making mathematical errors. It is important to carefully read and understand the problem, and double check your calculations to avoid these mistakes.

5. How can I apply my understanding of gravity to real-life situations?

Understanding gravity can help us explain and predict various phenomena in our daily lives, such as the motion of objects on Earth, the orbits of planets around the sun, and the tides in the ocean. It also has practical applications in fields such as engineering, aviation, and space exploration. By understanding gravity, we can better understand the world around us and make informed decisions in different situations.

Similar threads

I'm having trouble figuring out how to use the equation with G for gravity
Replies
17
Views
2K
Applying Newton's Universal Law of Gravitation
Replies
1
Views
945
Having trouble working out centripetal force?
Replies
4
Views
2K
Explaining How a Rotating Cylindrical Spaceship Simulates Gravity
Replies
3
Views
2K
How Does Apparent Weight Change for an Astronaut Near the Moon?
Replies
5
Views
3K
Problem using Newtonian Gravity.... Will you check my work?
Replies
4
Views
1K
Effect of zero gravity on spinal compression
Replies
6
Views
2K
How fast should the Earth spin for centripital accel. to equal gravity?
Replies
8
Views
2K
Centripetal Force / circular motion question
Replies
7
Views
3K
Artificial gravity in a spacecraft
Replies
17
Views
2K

Hot Threads

Recent Insights

Back
Top