Question

A ball is thrown vertically upward from the top of a tower with a velocity of 10 metre per second . the ball reaches the ground with a velocity of 30 metre per sec height of Towers

Answer 1

Explanation:

here,

u=10m/s

v=30 m/s

s=?

a=10m/s^2

v^2=u^2+2as

30^2=10^2+2×10s

900=100+20s

100+20s=900

20s=900-100

20s=800

s=800/2

s=40m

Answer 2

Answer:

Case 1 :

The ball is thrown upwards.

The initial speed = 0 m/s

The final speed = 10 m/s

The acceleration due to gravity = (-10) m/s²

Hence, using he third equation of motion :

⇒ v² - u² = 2as

⇒ 10² - 0² = 2×-10×s

⇒ 100 = -20s

⇒ s = 100/-20

⇒ s = -5 m

But, as the distance can't be negative, the distance is taken as 5 m.

Case 2 :

The ball falls downwards.

The initial speed = 10 m/s

The final speed = 30 m/s

The acceleration due to gravity = 10 m/s²

Hence, using the third equation of motion :

⇒ v² - u² = 2as

⇒ 30² - 10² = 2×10×s

⇒ 900 - 100 = 20s

⇒ 800 = 20s

⇒ s = 800/20

⇒ s = 40 m

Hence, the Distance travelled downwards = 40 m.

Now, the height of the tower = 40 - 5 = 35 m.