Question

A 500 g mass is dropped from 10 m above the
ground. What is its kinetic energy when it reaches
the ground? [Take g = 10 m/s?)​

Answer 1

Given

• Mass = 500 g
• Height = 10 m

To Find

• Kinetic Energy of the body when it reach the ground

Solution

● v = u + at [First Equation of Motion]

● Ke = ½mv²

✭ Velocity of the body :

→ v²-u² = 2as

→ v²-0² = 2 × 10 × 10

→ v² = 200

→ v = √200

→ v = 10√2

✭ Kinetic Energy :

→ Ke = ½mv²

• Mass = 500 g = 500/1000 = 0.5 kg
• Velocity = 10√2 m/s

→ Ke = ½ × 0.5 × (10√2)²

→ Ke = ½ × 0.5 × 200

→ Ke = 0.5 × 100

→ Ke = 50 J

∴ Kinetic Energy of the ball is 50 J

Answer 2

Answer:

Given :-

• Mass = 500 g
• Height = 10 m
• Acceleration due to gravity = 10 m/s

To Find :-

Kinetic energy when it reaches ground

Solution :-

For, finding Kinetic energy we will first find final velocity by using Newton first equation

v² = u² + 2as

v² = 0² + 2(10)(10)

v² = 0 + 200

v² = 200

v = √200

v = 10√2

Hence

Final velocity of body is 10√2 m/s

Let's find Kinetic energy

KE = ½ × mv²

KE = ½ × 0.5 × 10√2²

KE = ½ × 0.5 × 200

KE = 0.5 × 100

Hence :-

Kinetic energy of body is 50 J

$\rule{220}{10}$