Question

a ball is dropped from the height of 20 metres calculate the velocity with which the ball strikes the ground​

Answer 1

GIVEN :-

• u = 0m/sec
• s = 20m
• g = 10m/sec^2
• v = ?

SOLUTION :-

v^2 = u^2 + 2gs

v ^2 = 0^2 + 2(10)(20)

v ^2 = 400

➜v= 20m/sec..

∴ The ball strikes with velocity 20m/sec .

Answer 2

Height = 20 m

Initial velocity = 0 m/s (rest)

Acceleration = + 10 m/s² (downward)

We know,

$\boxed{2gh = v^2 - u^2}$

⇒ v² = 2gh

⇒ v = √(2gh) = √(2 × 10 m/s² × 20 m)

⇒ v = √2² × 10² × m²/s²

⇒ v = 2 × 10 m/s

⇒ v = 20 m/s (answer).

More:-

Equation of motion under influence of acceleration due to gravity and Height obtained:-

• $v = u ± gt$
• $h = ut ± \frac{1}{2} gt^2$
• $± 2gh = v^2 - u^2$.