Question

A student is testing the kinematic equations for uniformly accelerated motion by measuring the time it takes for
light-weight plastic balls to fall to the floor from a height of 3 m in the lab. The student predicts the time to fall
using g as 9.80 m/s2 but finds the measured time to be 35% greater. Which of the following is the most likely
cause of the large percent error?
(A) The acceleration due to gravity is 70% greater than 9.80 m/s2 at this location.
(B) The acceleration due to gravity is 70% less than 9.80 m/s2 at this location.
(C) Air resistance increases the downward acceleration.
(D) The acceleration of the plastic balls is not uniform.

Answer 1

(D) The acceleration of the plastic balls is not uniform is the most likely  cause of the large percent error.

Explanation:

The acceleration due to gravity = g = 9.8 m/s²

The 'g' slightly increases in the poles and slightly decreases in the equator.

Gravitational acceleration ∝ 1/(distance)²

Gravitational acceleration = k/(distance)²

Gravitational acceleration × (distance)² = k

Option A and option B are not possible as there is only slight increase and slight decrease in the poles and equator. The value of 'g' remains constant in the earth's surface.

Option C is wrong because when a object is drop from a height, the speed of the object increases with the object fall.

The option D is possible as the plastic ball is light weight, the acceleration of the ball is not uniform.