Question

A ball of mass 200g falls from a height 5m. What is its keinetic energy when it just reaches rhe ground (g=9.8m/p​

Answer 1

Given :-

• Mass of the ball (m) = 200 g
• Height (h) = 5 m
• Acceleration due to gravity (g) = 9.8 m/s²

To Find :-

• kinetic energy of the ball when it reaches the ground = ?

Solution :-

First convert the unit of the mass of ball from gram to kilogram :

• → Mass of ball = 200 g
• → Mass of ball = (200) ÷ (1000)
• → Mass of ball = 2 ÷ 10
• → Mass of ball = 0.2 kg

Hence,the mass of the ball is 0.2 kg.

According to the Question Now :-

Finding potential energy at higest point :

• → Potential energy = mass × Acceleration due to gravity × Height
• → Potential energy = 0.2 × 9.8 × 5
• → Potential energy = 1.96 × 5
• → Potential energy = 9.8 J

Hence,the potential energy of ball is 9.8 J.

• As we know that, the Potential energy at the highest point is equal to the Kinetic energy at the lowest point.

• Hence,from the above statement we can conclude that the Kinetic energy of the ball when it reaches the ground will be 9.8 J.

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Answer 2

Answer:- 9.8J

height = 5m

height = 5mmass = 200g

height = 5mmass = 200gpotential energy = mgh = 0.2 ∗ 5 ∗ 9.8 = 9.8J

height = 5mmass = 200gpotential energy = mgh = 0.2 ∗ 5 ∗ 9.8 = 9.8JSince potential energy at the highest point is equal to kinetic energy at lowest point , therefore kinetic energy will be 9.8J