Question

mary wants to remove a dent from a ping - pong ball without cutting into the sealed ball. she decides to put the ball in a bowl of boiling water. after a while, mary observes the dent disappearing until it is no longer present. why did the dent disappear? the water caused an increase in temperature of the air inside the ball and a decrease in pressure. the water caused an increase in temperature of the air inside the ball and an increase in pressure. the water caused a decrease in temperature of the air inside the ball and a decrease in pressure. the water caused a decrease in temperature of the air inside the ball and an increase in pressure. the water caused a decrease in temperature of the air inside the ball and an increase in pressure.

Explanation:

According to the ideal - gas law ($PV = nRT$), when the temperature ($T$) of the air inside the sealed Ping - Pong ball increases (due to the boiling water), with the volume ($V$) initially restricted by the dented shape and the amount of gas ($n$) and gas constant ($R$) remaining constant, the pressure ($P$) inside the ball increases. This increased pressure pushes the dented part outwards, causing the dent to disappear.

Answer:

The water caused an increase in temperature of the air inside the ball and an increase in pressure.