Question

A ball is thrown vertically upwords beta velocity of 25 metre per second from the top of a tower of height 30 m how long will it travel before you hit the ground

Answer 1

Answer :

›»› The time taken is 3 sec

Given :

• Initial velocity of a ball = 25 m/s
• The top of a tower height = 30 m

To Calculate :

• Time taken = ?

How to Calculate?

❒ Here in this question we have to calculate the time taken so we will use second equation of motion which says h = ut - ½ gt²

Here,

• h is the Height in m.
• u is the Initial velocity in m/s
• t is the Time taken in sec.
• g is the Acceleration due to gravity which is 10 m/s²

So let's calculate time taken..$.$

Calculation :

From second equation of motion

⇒ h = ut - ½ gt²

⇒ -30 = 25 × t - ½ × 10 × t²

⇒ -30 = 25t - ½ × 10 × t²

⇒ -30 = 25t - 5 t²

⇒ -6 = 5t - t²

⇒ t² - 5t - 6 = 0

⇒ (t - 3) (t + 2) = 0

⇒ t = 3 sec or t = - 2 sec

Time can't be in negative.

⇒ So, t = 3 sec

║Hence, the time taken is 3 sec.║