A 50 kg block is released from rest at a height of 20 m. What is the kinetic energy of the block jus

JAMB Physics 2023 76 views

A 50 kg block is released from rest at a height of 20 m. What is the kinetic energy of the block just before it hits the ground?

[g = 10 ms-2]

A 50 kg block is released from rest at a height of 20 m. What is the kinetic energy of the block just before it hits the ground?

[g = 10 ms-2]

  1. 5 kJ
  2. 40 kJ
  3. 15 kJ
  4. 10 kJ ✓

Explanation

Step 1: Identify given values and what to find
Given: m = 50 kg, h = 20 m, g = 10 ms⁻²
Find: Kinetic energy KE just before hitting ground

Step 2: Apply conservation of energy
Initial potential energy = Final kinetic energy
Formula: PE = mgh = KE

Step 3: Calculate potential energy (equals final KE)
PE = 50 × 10 × 20 = 10000 J = 10 kJ

Step 4: The answer is 10 kJ

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