Question

A stone dropper from a tower covers 15m in last second. What is the height of the tower?
1) 20m
2) 25m
3) 16m
4) 30m

Answer 1

Hello


According to the question , A stone is dropped from a tower . And it covers 15 m in last second .

In the question , 15 m is the distance travelled in last second ( We will use the formula of distance in nth second )

Formula :

$\boxed{\bold{s_{nth} = u + \frac{a(2n-1)}{2}}}$

Here , n = total time . S(nth) = 15 m and as the question is of free fall , a = g . u = 0 as the stone is dropped.


=> 15 = 10/2 * ( 2n-1)

=> 3 = 2n - 1
=> 2n = 4

=> n ( Total time ) = 2 sec


Let the total height of tower be H .


=> H = ut + 1/2 gt^2

t = 2 sec

=> H = 1/2 * 10 * 4


Height of tower = 20 m ( option 1 )








Hope It Helps You. ^_^

Answer 2

Answer:

1) 20m

Explanation:

A stone dropper from a tower covers 15m in last second. What is the height of the tower?

1) 20m ✓

2) 25m

3) 16m

4) 30m