Difficulty: Medium

Average Score: 67%

In which scenario does gravity cause the change in the object's motion?

Rationale

A skydiver accelerating towards the ground after jumping from a plane.

In this scenario, gravity is the primary force acting on the skydiver, causing them to accelerate downward. Gravity is a constant force that influences the motion of objects with mass, and in the case of a skydiver, it is the sole force responsible for their acceleration towards the Earth once they are in free fall.

A (A truck coming to a stop after applying the brakes) YOUR ANSWER

In this situation, the motion change is primarily caused by friction between the brakes and the wheels, not gravity. The truck decelerates due to the braking force, which counteracts its forward motion, making gravity a secondary factor at best.

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

The motion of the book is initiated by the external force applied by the person pushing it. While gravity acts on the book (keeping it on the table), it does not influence the horizontal motion directly; instead, friction between the book and the table is the primary force affecting its motion.

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

The acceleration of the speed skater is primarily due to the force exerted by their legs pushing against the ice and the resulting frictional force that propels them forward. Gravity does not play a significant role in this type of motion change, as the skater is already on a stable surface.

Conclusion

Gravity is the force that causes the change in motion for objects in free fall, as seen in the case of a skydiver. While forces such as friction and applied force can influence motion in other scenarios, gravity's role in accelerating the skydiver towards the ground exemplifies its unique impact on motion when no other forces counteract it. Understanding this distinction is crucial in physics when analyzing forces and motion.

Related Questions

View all