Work, Power and Energy Part 1

Assume the ball of mass m is projected with a speed u. Then the kinetic energy(E) at the point of projection =‌

1

2

mu2
At highest point of flight only horizontal component of velocity u‌cos‌θ present as at highest point vertical component of velocity is =0.
Note : The horizontal component of velocity does not change in entire projectile motion.
At highest point the velocity is =u‌cos‌θ=u‌cos‌45∘=‌

u

√2

∴ The kinetic energy at the height point =‌

1

2

m(‌

u

√2

)2
=‌

1

2

mu2×‌

1

2

=‌

E

2