Question

Hickers stands at the edge of a cliff 490 m above the ground and throw stone horizontally with an initial speed 15 M per second. neglecting a resistance find the time taken by the stone to reach the ground, find the range and the speed with which it hits the ground and also calculate its direction

Answer 1

Range = horizontal distance covered.

We will use the following equations of motion :

V² = U² + 2gs

S = ut + 1/2gt²

V = u + gt

1.) time taken to reach the ground

S = ut + 0.5gt²

490 = 15t + 5t²

Divide through by 5

t² + 3t - 98 = 0

We use quadratic formula to solve :

t = {- 3 +/-√9 + 392} /2

t = (-3 +/-59.40) /2

t = 28.2 or - 31.2

We take the positive value.

t = 28.2 seconds.

2.) Range

Range = ut

Range = 15 × 28.2 = 423 M

3.) Final velocity

V = u + at

V² = u² + 2gs

V² = 225 + 2 × 10 × 490

V² = 225 + 9800

V² = 10025

V = √10028

V = 100.12 m/s