Question 13

Friction causes the velocity of a tossed coin to decrease when it sinks through the water in a wishing well.

When a coin is tossed into water, friction between the coin's surface and the water molecules opposes its motion, leading to a decrease in its velocity as it sinks.

A) Friction

This option is correct because friction is the force that acts in the opposite direction to the motion of the coin as it moves through the water. The resistance from water molecules creates drag on the coin, effectively slowing it down.

B) Gravity

While gravity acts on the coin, pulling it downward, it does not cause a decrease in velocity; instead, it contributes to the acceleration of the coin as it sinks. Gravity works to increase the speed of the coin rather than decrease it.

C) Magnetism

Magnetism is not a relevant force in this context, as the coin is not magnetic and there is no magnetic field affecting its motion in the water. Thus, this option does not apply to the scenario described.

D) Tension

Tension refers to the force exerted by a string or rope when it is pulled tight. Since there is no rope or string involved in the sinking of the coin, this option is not applicable to the situation.

Conclusion

Friction is the primary force responsible for reducing the velocity of the coin as it enters the water, while gravity, magnetism, and tension do not apply in the same context. Understanding the role of friction in fluid dynamics is essential to grasp how objects behave when submerged.