Question

A body is projected at an angle 60° from surface
of earth with velocity √2gR. Final K.E. of object
is (symbols have usual meanings)
(1) Zero
(2) mgR
3)mgR/2
(4) Infinite​

Answer 1

Answer:(2)mgr

Explanation: Using conversion of kinetic energy as initial and final level of body is same.

Answer 2

answer : option (2) mgR

explanation : when a particle is projected with speed u at an angle θ, it will strike the ground with same speed u ( just opposite in direction)

so, final speed of body , v = √2gR

and then final kinetic energy = 1/2 mv²

= 1/2 m(2gR)

= mgR

[ don't confuse to see escape velocity √2gR, effective speed of particle in vertical direction is √2gR sin60° = √(3gR/2) < √2gR ]

also read similar questions :A particle is projected upward from the surface of earth(radius R) with a K.E. equal to half the minimum value needed fo...

https://brainly.in/question/64160

What must be the velocity of a moving body of mass 2 kg so that its K.E is 25 J ?

https://brainly.in/question/1129656