Answer to Question #125652 in Mechanics | Relativity for Ahad

Question

A tennis ball of mass 56 gm is projected vertically upward with average velocity 48.1 m/s. Calculate the kinetic energy after 5 seconds

Answer 1

$KE=\frac{mv^2}{2}$

$v_f=v_0-gt$

When $v_f=0$ $t=4.903s$

So,

$5-4.903=0.097s$

In this case

$v_f=v_0+gt=0+gt=gt=9.81\cdot0.097=0.95m/s$

Finally

$KE=\frac{mv^2}{2}=\frac{0.056\cdot 0.95^2}{2}\approx0.03J$