Register to reply

Motion with changing mass

by athrun200
Tags: mass, motion
Share this thread:
athrun200
#1
Oct16-11, 06:19 AM
P: 277
1. The problem statement, all variables and given/known data
http://www.physicsforums.com/attachm...1&d=1318764025

2. Relevant equations
F=m[itex]\frac{dv}{dt}[/itex]-v[itex]\frac{dm}{dt}[/itex]


3. The attempt at a solution
It seems part b is trivial. Obviously, the propellsion force is constant. To find F, just subs m=m/2

I am not sure wheather I am right.

http://www.physicsforums.com/attachm...1&d=1318764025
Attached Thumbnails
2.JPG   1.jpg  
Phys.Org News Partner Science news on Phys.org
Physical constant is constant even in strong gravitational fields
Montreal VR headset team turns to crowdfunding for Totem
Researchers study vital 'on/off switches' that control when bacteria turn deadly
Spinnor
#2
Oct16-11, 01:15 PM
P: 1,376
Why should the propulsion force be constant? As the water level goes down the water pressure at the bottom of the bucket will be lower so the water velocity will be less?
athrun200
#3
Oct16-11, 10:18 PM
P: 277
Quote Quote by Spinnor View Post
Why should the propulsion force be constant? As the water level goes down the water pressure at the bottom of the bucket will be lower so the water velocity will be less?
I know the force depends on the ejected speed, but the question state that its speed is constant, that's why I say it is constant and the whole question becomes very esay.


Register to reply

Related Discussions
What happens to Newton's 2nd law if there is a changing mass? Classical Physics 3
Momentum with changing mass Introductory Physics Homework 7
Changing mass of the sun Astronomy & Astrophysics 1
Changing Mass Special & General Relativity 5
The changing mass of the sun General Physics 3