Planet and speff problem find mass

  • Thread starter Thread starter physicsgurl12
  • Start date Start date
  • Tags Tags
    Mass Planet
Click For Summary
To find the mass of planet X, the gravitational force equations are utilized, specifically F = G·m1·m2/r². Spaceman Speff's weight at the planet's surface is 389N, and at a height of 1.86*10^4 km, it is 24.31N. Two equations are established using these weights to solve for the mass of the planet, with Speff's mass given as 75 kg. The calculated mass of planet X is 2.96*10^24 kg. This approach effectively applies gravitational principles to determine planetary mass based on weight changes at different distances.
physicsgurl12
Messages
184
Reaction score
0

Homework Statement


The weigh tof spaceman speff, soley due to the gravitational pull of planet x at its surface is 389N. If he moves to a distance of 1.86*10^4km above the planets surface his weight changes to 24.31N. What is the mass of planet xif speffs mass is 75 kg.


Homework Equations



f=ma
f=gm1+m2/r^2

The Attempt at a Solution


i know the answers is 2.96*10^24 kg. nut idk how to get it
 
Physics news on Phys.org
I would double check your second equation.
 
it m1*m2
 
what else?? I am still not getting it
 
Use the F=G·m1·m2/r2 equation, and plug in the given information. There are two sets of information, so you would get two equations:

(1) 389 N = G · __ · __ / __
(2) Use the other weight given in the problem to set up the second equation
 

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?
View full post »

Similar threads

Determine the mass of the planet using Newton’s Law of Universal Gravitation
  • · Replies 2 ·
Replies
2
Views
3K
Calculating mass of a planet (Law of Universal Gravitation)
  • · Replies 2 ·
Replies
2
Views
4K
Weight of person on Earth, and on a different planet's surface?
  • · Replies 11 ·
Replies
11
Views
3K
Finding the Kinetic Energy using the mass, radius and initial KE
  • · Replies 12 ·
Replies
12
Views
2K
Weight of an Object on another Planet
  • · Replies 1 ·
Replies
1
Views
1K
Finding the astronaut's weight on a planet's surface
  • · Replies 9 ·
Replies
9
Views
3K
How to find the mass of a planet when given the radius?
  • · Replies 1 ·
Replies
1
Views
2K
Mass of planet expressed as multiple of earth's mass
  • · Replies 3 ·
Replies
3
Views
2K
Gravitational Acceleration given mass and radius
  • · Replies 3 ·
Replies
3
Views
3K
Does a Planet's Atmosphere Affect an Astronaut's Weight?
  • · Replies 3 ·
Replies
3
Views
2K