Question

a body is projected at angle 60 with horizontal ground with kinetic energy k. When the velocity makes an angle 30 with the horizontal. Then the kinetic energy of the body will be ​

Answer 1

Explanation:

initial velocity=v

projectile starts with 60°

the horizontal component of velocity is same throughout the projectile.

Horizontal component = v• cos 60°

At the point at which the projectile becomes 30°

cos 30° = v horizontal/v

or

v = v horizontal / cos 30°

which gives us v= 0.577 •v

Kinetic energy at beginning KE = 1/2 • m • v square.

Kinetic energy when projectile at 30° = KE30° = 1/2 •m•(0.577•v square)

Therefore, kinetic energy when projectile at 30° becomes 0.3333 • KE