- #1
wirefree
- 105
- 21
Question: A glass half filled with water is kept on a horizontal table in a train. Will the free surface of water remain horizontal as the train starts? If not, which way would it tilt?
Attempt: I know this is similar to the 'passenger in a bus' situation discussed in texts. I've identified the following forces:
1) 'mg': the force acting on TRAIN/GLASS due to the WATER
2) 'ma': the force acting on WATER due to the TRAIN/GLASS (in the direction of train's motion)
3) '-ma': the force acting on TRAIN/GLASS due to the WATER (applying Newton's 3rd Law)
Problem: Given that the above force definitions are correct, I cannot appreciate how the force that should push the water backward, i.e. '-ma', isn't actually acting on it!?
Perplexed,
wirefree
Attempt: I know this is similar to the 'passenger in a bus' situation discussed in texts. I've identified the following forces:
1) 'mg': the force acting on TRAIN/GLASS due to the WATER
2) 'ma': the force acting on WATER due to the TRAIN/GLASS (in the direction of train's motion)
3) '-ma': the force acting on TRAIN/GLASS due to the WATER (applying Newton's 3rd Law)
Problem: Given that the above force definitions are correct, I cannot appreciate how the force that should push the water backward, i.e. '-ma', isn't actually acting on it!?
Perplexed,
wirefree