Suppose a bus is moving with constant speed with so many passenger in it (so that they have a considerable mass with respect to the bus). What are the changes observed in the motion of bus if all the passengers jump at once all together?
Answers
Answer:
Let us take both passengers and bus as a system . There is no external force so Centre of Mass of both bus and passenger will be moving with same velocity v .
In horizontal direction it is easy to think that every thing is moving with v and also will be because there is no external force to change motion ( Newton ' s first law )
In vertical when all passengers jumps COM shifts a little up to balance that bus will try to go downwards , which is not possible .
I think it is easy to understand by action - reaction law . All passengers will apply force on bottom in bus for jump .
Finally all forces will cancel out and there will be no effect .
Notes :
In real life mass may not be distributed uniformly , so force may be zero but torque won't . So bus can flip over .
