Answer to Question #216763 in Physics for Sadia Shafique

Question

1) A 6.5 kg ball is launched upwards from the ground with a speed of 21 m/s.

a) How much kinetic energy does the ball have?

b) If all of the ball's kinetic energy is converted to gravitational potential energy, how high will the ball go?

Answer 1

(a)

$$KE=\dfrac{1}{2}mv^2,$$ $$KE=\dfrac{1}{2}\cdot6.5\ kg\cdot(21\ \dfrac{m}{s})^2=1433.25\ J.$$

(b)

$$KE=GPE=mgh,$$ $$h=\dfrac{KE}{mg}=\dfrac{1433.25\ J}{6.5\ kg\cdot9.8\ \dfrac{m}{s^2}}=22.5\ m.$$