Question

A body is projected at an angle 30 degree to the horizontal with kintic energy E.The kinetic energy at the topmost point is?

Answer 1

E=m•vₒ²/2
vₒ=sqrt(2•E/m).
At the top point v(y) = 0.
The velocity of the body =v(x)=v(ox)
v=v(0x) =vₒ•cosα.
E(kin) = mv²/2=
= m(vₒ•cosα) ²/2=
= m• (2•E/m) •cos²α /2=
=2•E• cos²α/2= E• cos²α=0.75E

Answer 2

E/2