Free Fall & Acceleration Due to Gravity

Explore how all objects fall at the same rate in the absence of air resistance, and learn about the constant acceleration due to Earth's gravity.

0 m/s
h = 10m
7.5m
5m
2.5m
Mode:
Free Fall
VACUUM
Force and Acceleration
F = mg
The gravitational force on an object equals its mass times the acceleration due to gravity.
Value of g
g = GM/R² = 9.8 m/s²
Where G is the universal gravitational constant, M is Earth's mass, and R is Earth's radius.
Equations of Motion
v = u + gt
s = ut + ½gt²
v² = u² + 2gs
These equations describe motion under constant acceleration due to gravity.
Example 9.2 (from NCERT): A car falls off a ledge and drops to the ground in 0.5 s.
Let g = 10 m/s² (for simplifying calculations)
Find: (i) Speed on striking the ground
(ii) Average speed during the 0.5 s
(iii) Height of the ledge from the ground
Given Values:
Time, t = 0.5 s
Initial velocity, u = 0 m/s (dropped, not thrown)
Acceleration due to gravity, g = 10 m/s²
Acceleration of the car, a = +10 m/s² (downward)
(i) Speed on striking ground:
v = u + at
v = 0 + 10 × 0.5
v = 5 m/s
(ii) Average speed:
Average speed = (u + v)/2
= (0 + 5)/2
= 2.5 m/s
(iii) Height of ledge:
s = ut + ½at²
s = 0 × 0.5 + ½ × 10 × (0.5)²
s = ½ × 10 × 0.25
s = 1.25 m
(i) Speed on striking ground = 5 m/s
(ii) Average speed = 2.5 m/s
(iii) Height of ledge = 1.25 m
Explore Free Fall
Activity 9.2: Stone Throw Experiment
Activity 9.3: Paper and Stone Comparison
F = mg
From the text: "The magnitude of the gravitational force F will be equal to the product of mass and acceleration due to the gravitational force"

Value of g: g = GM/R² = 9.8 m/s²
Where G = 6.7 × 10⁻¹¹ N m² kg⁻², M = 6 × 10²⁴ kg (Earth's mass), R = 6.4 × 10⁶ m (Earth's radius)
Equations of Uniformly Accelerated Motion (with a = g):
(i) v = u + gt
(ii) s = ut + ½gt²
(iii) v² = u² + 2gs
Note: Acceleration is positive when in direction of motion, negative when opposing motion.
For upward motion: a = -g (opposing velocity)
For downward motion: a = +g (same direction as velocity)