Launching from Mars - Mass & Radius of R_m

  • Thread starter Thread starter soupastupid
  • Start date Start date
  • Tags Tags
    Mars
Click For Summary

Homework Help Overview

The problem involves launching an object from just above the atmosphere of Mars, with the radius of Mars denoted as R_m and its mass as m. The original poster seeks to determine the object's initial velocity given its final velocity, V_f, while grappling with the implications of gravitational forces and work-energy principles.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of Newton's universal law of gravitation and the relationship between force, mass, and distance. Questions arise regarding the calculation of gravitational acceleration and the work done by Mars. There is uncertainty about how to approach the problem without specific numerical values and how to define certain variables like distance and initial velocity.

Discussion Status

The discussion is active, with participants offering various approaches and equations related to gravitational force and energy. Some express confusion about the relevance of work in this context and the need for numerical values, while others attempt to clarify the relationships between the variables involved.

Contextual Notes

Participants note the lack of specific numerical values and express concern that this may hinder their ability to solve the problem effectively. There is also a mention of the need for clarity regarding the definitions of certain terms and variables used in the equations.

soupastupid
Messages
34
Reaction score
0

Homework Statement


The Radius of Mars is R_m
its mass is m

The radius of Mars (from the center to just above the atmosphere) is R_m and its mass is m. An object is launched from just above the atmosphere of mars.

A) what is the object's initial velocity if its final velocity is V_f

Homework Equations



a=(v^2)/R <--wat v is this?
W=deltaKE

The Attempt at a Solution



i don't know how to start

im thinking i need to calculate the gravity from mars?
but if all I am given is mass and radius
how do i calculate it?

i need to find the amount of work done by Mars right?
 
Last edited:
Physics news on Phys.org
I think you need to use Newtons universal gravity law...

F=(GM1M2)R^2

This means that the force is equal to the constant G (6.67X10^-11) multiped by both masses, all of this divided by the distance between them squared.

this will get you the Force.

So now you have force, you know that Fnet=ma, so the acceleration will be {(Gm1m2)/R^2}/m

finally, Vf^2-Vo^2=2a(x), so you simply solve using the above equation as a, and they just say to use Vo i believe
I don't think this is a problem you shoudl get numbers for, it seems like a concept that you just want to work through with different equations and not really use numbers.

This is just from what I understand.

Good luck!
 
im solving for Vo

the object is launched from above the atmosphere

im given the distance between object and Mars (R_m)
and I'm given the weight of Mars (m)

and I'm given Vf of the object

so what I did (but I did not get a good answer)

was use

F=Gm1m2/r^2

m1 = object
m2 = mars
r=distance from Mars and object

so the F equals

F= Gm1m2/(R_m)^2

and then I think I'm suppose this formua

total W = deltaKE

F*d = .5m1vf^2 - .5m1vo^2

but how do I find d?

I think this is right

how do I use

vf^2-vo^2 = 2a (x) <--whats x ?
 
With what you have you won't be able to find work and finding energy is also not going to work out. I can't help if you don't supply numbers, I solved it simply with the units, plugging the numbers in should have yielded the answer.

From what I can understand by your explanation that is anyway, it doesn't seem like work is in anyway involved.
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
6
Views
5K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 11 ·
Replies
11
Views
6K
  • · Replies 6 ·
Replies
6
Views
16K
  • · Replies 6 ·
Replies
6
Views
3K