Question 52

A skydiver accelerating towards the ground after jumping from a plane

Gravity is the force that pulls the skydiver towards the Earth, causing them to accelerate downwards after they jump from the plane. This motion is directly influenced by the gravitational force acting on the skydiver.

A) A truck coming to a stop after applying the brakes

While the truck's motion changes, this scenario involves the application of brakes which creates friction, not gravity. The primary force at work here is the braking force, which opposes the truck's motion, rather than gravitational influence.

B) A book sliding across a table after being pushed by someone

In this case, the book's motion is altered due to the force applied by the push, and the friction between the book and the table. Gravity acts on the book, but it does not cause the change in motion; instead, it is the initial push that initiates the sliding.

C) A speed skater accelerating across the ice after the starting gun

The acceleration of the speed skater is a result of the skater's own propulsion and the force applied to the ice. Gravity affects the skater's weight but does not directly cause the change in motion as the skater accelerates from the starting position.

D) A skydiver accelerating towards the ground after jumping from a plane

This scenario exemplifies gravity's role in changing an object's motion. Once the skydiver exits the plane, gravity is the dominant force acting on them, pulling them downward and causing acceleration towards the Earth.

Conclusion

The correct answer, D, highlights the essential role of gravity in changing an object's motion, as seen with the skydiver. In contrast, the other options primarily involve different forces or influences that do not directly relate to gravitational effects on motion. Thus, they do not fulfill the requirement of the question regarding gravity's role in motion change.