Question

A tennis ball is thrown in the vertically upward direction and the ball attains a maximum height of 20 m. The ball was thrown approximately with an upward velocity of
1. 8 m/s
2. 12 m/s
3. 16 m/s
4. 20 m/s

Answer 1

Correct Answer - Option 4 : 20 m/s

The correct answer is option 4) i.e. 20 m/s

CONCEPT:

Kinematic equations of motion:

• These equations define the relationship between initial velocity u, final velocity v, time t, and displacement s of an object with respect to its motion in uniform acceleration a.
• Following are the three kinematic equations for uniformly accelerated motion:

⇒ v = u + at

⇒ s = ut + 0.5at2

⇒ v2 - u2 = 2as

CALCULATION:

Given: Height, s = 20 m

• Since the ball attains a maximum height, therefore the final velocity v = 0 m/s
• The ball was thrown approximately with an upward velocity of

⇒ v2 - u2 = 2as

⇒ 02 - u2 = -2 × 10 × 20

⇒ u² = 400

⇒ u = 20 m/s