Question

From the top of the tower of height 80m, two stones are projected horizontally with 20 m/s and 30m/s in opposite directions. Find the distance between the stones on reaching the ground

Answer 1

the distance between the stones on reaching the ground is 200 metre.

Answer 2

Given : From the top of the tower of height 80 m, two stones are projected horizontally with 20 m/s and 30 m/s in opposite directions.

To find : the distance between the stones on reaching the ground.

solution : It is based on concept of Horizontal projectile.

horizontal range , R = u√{2H/g}

case 1 : H = 80 m, u₁ = 20 m/s

so, horizontal range of 1st stone, R₁ = u₁√{2H/g}

= 20 × √{2 × 80/10}

= 20 × √16

= 80 m

case 1 : H = 80 m, u₂ = 30 m/s

so, horizontal range of 2nd stone, R₂ = u₂ √{2H/g}

= 30 × √{2 × 80/10}

= 30 × √16

= 120 m

as both stone are projected in opposite directions.

so, the distance between the stones on reaching the ground = R₁ + R₂

= 80 m + 120 m

= 200 m

Therefore the distance between the stones on reaching the ground is 200 m.