Question 52

A skydiver accelerating towards the ground after jumping from a plane

Gravity is the primary force acting on the skydiver, causing them to accelerate towards the ground after they jump from the plane. This scenario clearly demonstrates how gravity influences an object's motion by pulling it downward.

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

While this scenario involves a change in motion, it is primarily due to friction and the application of brakes rather than gravity. Gravity does not significantly affect the truck's motion in this context, as the stopping force is generated by the brakes acting against the truck's momentum.

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

In this case, the change in motion of the book is caused by the force applied by the person pushing it. Gravity acts on the book but does not influence its horizontal motion across the table; instead, the motion is primarily a result of the initial push.

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

The acceleration of the speed skater is due to the force exerted by their legs against the ice, propelling them forward. Gravity does not play a significant role in the skater's change of motion in this scenario, as their movement is primarily horizontal and not influenced by gravitational pull.

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

This scenario illustrates the effect of gravity directly, as the skydiver is in free fall, accelerating towards the Earth due to gravitational force. The motion is clearly dictated by gravity's pull, making this the correct answer.

Conclusion

The correct answer is D, as it directly illustrates how gravity affects an object's motion. In contrast, options A, B, and C describe changes in motion that are influenced by other forces such as friction or applied force, rather than gravitational force. Therefore, D is the only option that aligns with the question's focus on gravity's role in motion change.