Register to reply

Relative motion of a dropping object on a moving train

by MechaMZ
Tags: dropping, motion, moving, object, relative, train
Share this thread:
Sep5-09, 11:59 PM
P: 129
1. The problem statement, all variables and given/known data
A bolt drops from the ceiling of a train car that is accelerating northward at a rate of 3.50 m/s2.
(a) What is the acceleration of the bolt relative to the train car?
(b) What is the acceleration of the bolt relative to the Earth?

3. The attempt at a solution
(a)10.4 m/s2 at 19.7 to the south from the vertical
(b)9.8 m/s2 vertically downward

I don't understand why the acceleration in (a) is not vertically downward since it is relative to the train. As we could assume the train is not moving, then the motion should be vertically downward isn't?
Phys.Org News Partner Science news on
Scientists develop 'electronic nose' for rapid detection of C. diff infection
Why plants in the office make us more productive
Tesla Motors dealing as states play factory poker
Sep6-09, 12:24 AM
P: 179
The train is accelerating. So the instant the bolt starts to drop you would see it going vertically downward if you were on the train. Now since the train is accelerating the bolt appears to be moving backwards since the train is speeding up but the bolt is not.

Register to reply

Related Discussions
Relative Motion Question Involving Rain and Moving Car Introductory Physics Homework 3
Projectile Motion/Dropping an object from the sky Introductory Physics Homework 8
Is motion relative to the size of an object Special & General Relativity 18
Dropping an object from a moving plane. Introductory Physics Homework 5
Will an object moving at a constant motion... General Physics 3