An object is dropped from a certain height in a region where there is no air resistance (that is, it is in free fall). What happens to its speed and acceleration as it falls?

Introduction / Context:

This conceptual physics question is about free fall motion near the Earth surface. When an object is dropped from rest in the absence of air resistance, its motion is governed only by the gravitational force. Understanding how speed and acceleration behave in this idealised situation is essential for solving many kinematics and dynamics problems in mechanics.

Given Data / Assumptions:

• An object is released from rest at some height above the ground.
• No air resistance or other forces act, only the gravitational force.
• Acceleration due to gravity is taken as g, approximately 9.8 m/s^2, directed downward.
• We are interested in how both speed and acceleration change during the fall.

Concept / Approach:

In free fall, the only force acting on the object is its weight, mg, downwards. Newton’s second law then gives a constant downward acceleration equal to g. Because acceleration is constant, the velocity of the object increases linearly with time from its initial value of zero. Speed, which is the magnitude of velocity, therefore increases steadily, while the acceleration remains constant in magnitude and direction throughout the fall.

Step-by-Step Solution:

Verification / Alternative check:

The standard equations of uniformly accelerated motion support this. For example, displacement s = 0.5 * g * t^2, velocity v = g * t, and acceleration a = g, all derived from constant acceleration. Laboratory experiments using vacuum tubes or drop towers confirm that bodies in free fall without air resistance all accelerate at the same constant rate, regardless of mass. These facts are consistent only with increasing speed and constant acceleration.

Why Other Options Are Wrong:

• It will fall with constant speed and constant acceleration: Constant acceleration cannot coexist with constant speed; if acceleration is non zero, speed must change.
• Its acceleration will keep on increasing as it falls: In the free fall model, gravitational acceleration near the Earth surface is taken as constant g, not increasing with time.
• Both its speed and its acceleration will keep increasing together: Speed increases, but acceleration remains constant, so this statement is incorrect.

Common Pitfalls:

Many learners confuse acceleration with speed and think that if an object is speeding up, its acceleration must also be increasing. Another common mistake is to imagine that gravity somehow becomes stronger as the object approaches the ground in simple school level problems; however, we treat g as approximately constant over the small height changes involved. Keeping the distinction clear between velocity, speed, and acceleration helps to avoid these misunderstandings.

Final Answer:

In free fall without air resistance, the object speed increases while its acceleration remains constant.