Question

A stone of mass 1.0kg is dropped from a certain height and takes 8 seconds for the stone to strike the sandy ground, upon reaching the ground the stone penetrate 5.0 into the ground ( take g=10m/s) A)calculate de height from where the stone is dropped?

Answer 1

`H_"total"=325m`

Explanation:

Acceleration due to gravity `=+g=10m//s^2`
Initial velocity`=0m//s`
Time taken for Stone to hit the ground `=8secs`
`H_1=5.om`
Applying eqns of motion under gravity
V `=`u + gt
V `=` `0 +`(`10`x`8`)
V `=` `80m//s`
Recall:
`v^2=u^2 +2gH`
Let `H_2=`height to ground level
`80^2=0^2 + 2`(`10H_2`)
`6400-0= + 20H_2`
`6400=20H_2`
`H_2=(6400)/20`
`H_2=320m`
Total height`=H_1+H_2`
`=(320+5)m`
`=325m`