Question

Discuss the motion of body thrown from certain height

Answer 1

Generally, the motion of a body thrown from a certain height is called projectile motion.

When a body is thrown obliquely into the space, it traces a path along a curve under constant acceleration that is directed towards the centre of the earth. The path of the body thrown is called projectile and the angle made with the horizontal while throwing is called the angle of projection.

Answer 2

Let a body of mass m is thrown from certain height h with speed u, after time t body reaches the ground.

use equation, S = ut + 1/2 at²

when we consider reference level at the top of height h,

then, S = -h, initial velocity = -u and a = -g

so, -h = -ut + 1/2(-g)t²

=> h = ut + 1/2 gt²

here it is clear that, graph between displacement and time is parabolic and increasing. means, to increase the time, increases the length of distance covered by body and decreases the separation between body and ground.

again, use formula, v² = u² + 2as

here, initial velocity = -u , a = -g and s = -h

so, v² = (-u)² + 2(-g)(-h)

=> v² = u² + 2gh

=> v = √(u² + 2gh)

hence, when we through the body from a certain height h, speed of body before striking the ground greater than initial velocity of body.