Jimi (80 kg) and Tony (100 kg) stand motionless on ice skates, facing each other at arm's length on a smooth, frozen pond. Which of the following actions will give Tony the greatest speed?
To find out which action will give Tony the greatest speed, we need to analyze the concept of momentum conservation. According to the law of conservation of momentum, the total momentum before an interaction is equal to the total momentum after that interaction.
Since both Jimi and Tony are initially motionless, their total momentum before any action is zero (since the momentum is mass multiplied by velocity, and both have zero velocity).
Let's analyze the different actions:
1. Jimi pushes Tony directly away from himself:
In this case, Jimi imparts momentum to Tony, which will cause Tony to start moving away from Jimi.
As a result, Tony will gain momentum, and this will lead to Tony having a non-zero velocity while Jimi's velocity remains zero.
2. Jimi pulls Tony towards himself:
In this case, Jimi again imparts momentum to Tony, but in the opposite direction. This action will cause both of them to move towards each other.
Since the total momentum before the action is zero, the total momentum after the action must also be zero. Therefore, if Tony gains momentum and starts moving towards Jimi, Jimi must lose equal momentum and move backward.
3. Jimi and Tony begin pushing against each other equally:
If they push against each other with equal force, their momentum will remain zero because the momentum gained by one person will be canceled out by the momentum lost by the other person. Therefore, neither of them will experience a change in momentum or velocity.
Looking at these actions, it is clear that the first action (Jimi pushing Tony directly away from himself) will give Tony the greatest speed.