2.5 Motion Due to Gravity

Key Points:

  • All freely falling objects have the same acceleration due to gravity (g), independent of their masses.
  • Near Earth's surface, g ≈ 9.80 m/s² or 32.2 ft/s²
  • Acceleration due to gravity is directed downward, toward the Earth's center.
  • For large objects, air resistance is often neglected.
  • When an object moves with gravity: +g; against gravity: -g

Air Resistance Effects:

With Air

Coin falls faster

Without Air

Both fall at same rate

Example 2.5: Acceleration Due to Gravity

Given: Mass = 2 kg, Initial speed = 0 m/s, Final speed = 78.5 m/s, g = 9.8 m/s²

Required: Time to reach the ground

Solution: ∆t = (v₂ - v₁) / g = (78.5 - 0) / 9.8 = 8 s

Result: The block will reach the ground in 8 seconds.

Interactive Example: Free Fall Calculator

Calculate the time for an object to fall from a given height: