Acceleration of free fall - Higher

The acceleration of a falling object can be calculated using Newton’s Second Law, F = ma

If a skydiver has a mass of 60 kg. Her weight is found using:

W = mg

W = 60 kg x 10 N/kg

W = 600 N

If air resistance is ignored, the pull of gravity, 600 N, is the only force acting on the skydiver. Her acceleration is found using:

a = \frac{\text{F}}{\text{m}}

F = 600 N

m = 60 kg

a = \frac{\text{600 N}}{\text{60 kg}}

a = 10 m/s2.

Key points

  • In the absence of air resistance all objects fall at the same rate regardless of their mass. Near the Earth the rate is the acceleration of free fall, 10 m/s2.
  • Due to the Earth’s gravity, the speed of an object dropped from a height will increase at a rate of 10 m/s every second as it falls.
  • If there was no air resistance or drag, a feather and a hammer would fall at the same rate of 10 m/s2. Dropped from the same height, they would both hit the ground at the same time and travelling at the same speed.