Question

A stone drooped from the top of a tower reaches the ground in 8 second (a=10ms^-2) .calculate :
A)the height of the tower
B)the distance travelled by the stone in the 8th second

Answer 1

$\bigstar$ Given :

A stone dropped from the top of a tower reaches the ground in 8 seconds

$\bigstar$ To Find :

A) The height of the tower

B) The distance travelled by the stone in the 8th second

$\bigstar$ Solution :

Here ,

Time , t = 8 seconds

Distance , s = ?

Initial velocity , u = 0

Acceleration due to gravity , a = g = 10 m/s²

Use 2nd equation of motion .

⇒ s = ut + ¹/₂ at²

⇒ s = ¹/₂ (10)(8²)

⇒ s = 5 * 64

A) ⇒ s = 320 m

Now ,

Distance covered by moving body in nth second of journey is given by

$\bigstar\:\underline{\boxed{\bf{\red{s_n=u+\dfrac{a}{2}(2n-1)}}}}$

$\implies \bf s_8=0+\dfrac{10}{2}(2(8)-1)\\\\\implies \bf s_8=5(15)\\\\\bf B)\implies \bf s_n=75\ m$

Answer 2

Answer:

height - 320m and distance - 75 m