Two metal balls with the same mass hang so that they are touching each other. The ball on the left is pulled to the side and released. What will happen when it swings back and hits the ball on the right?
a Both balls will swing to the right.
b Both balls will swing to the left.
c The ball on the left will stop, and the ball on the right will remain still.
d The ball on the right will swing to the right.
a Both balls will swing to the right.
The correct answer is:
b) Both balls will swing to the left.
When the ball on the left is pulled and released, it swings as a pendulum due to gravity. As it swings back to its original position, it transfers its kinetic energy to the ball on the right through the collision. This causes the ball on the right to start swinging in the opposite direction, to the left. Hence, both balls will swing to the left.
To determine what will happen when the left ball swings back and hits the right ball, we can analyze the scenario using the principles of conservation of energy and momentum.
When the left ball is pulled to the side and released, it starts swinging back due to the force of gravity acting on it. As it swings back, it gains potential energy, which is then converted to kinetic energy as it starts moving. At the peak of its swing, the left ball will have maximum potential energy and zero kinetic energy. At the bottom of the swing, it will have maximum kinetic energy and zero potential energy.
Now, when the left ball swings back and hits the right ball, several things can happen depending on the nature of the collision.
If the collision is perfectly elastic (no energy is lost during the collision), the left ball will transfer some of its kinetic energy to the right ball upon impact. As a result, both balls will swing away from each other, conserving the total momentum of the system. In this case, the answer would be option (a) - both balls will swing to the right.
If the collision is partially elastic (some energy is lost during the collision), the balls are likely to stick together and move as one unit. In this case, the left ball will come to a stop upon impact, and the right ball will start moving in the direction of the impact. The answer would then be option (d) - the ball on the right will swing to the right.
However, if the collision is completely inelastic (maximum energy is lost during the collision), both balls will stick together and come to a stop upon impact. The answer would then be option (c) - the ball on the left will stop, and the ball on the right will remain still.
Therefore, without additional information about the nature of the collision (whether it is elastic, partially elastic, or completely inelastic), it is not possible to determine the exact outcome.