A toy rocket that weighs 10 N blasts straight up from ground level with an initial kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height above the ground does it rise, assuming no air resistance?

10 m

Explanation:

Weight = 10 N

mg = 10

m = 10 / 10 = 1 kg

g = 10 m/s^2

Initial mechanical energy = 40 J

Final mechanical energy = 140 J

change in total energy = 140 J - 40 J = 100 J

At the maximum vertical height, the velocity = 0 m/s

So, it has only potential energy at maximum height

P = m x g x h

100 = 1 x 10 x h

h = 10 m