Acannonball is fired with initial speed v0 at an angle 30° above the horizontal from a height of 40 m above the ground. the projectile strikes the ground with a speed of 1.2v0. find v0. (ignore any effects due to air resistance.)

Explanation:

We shall use conservation of energy to solve this problem

Initial energy of the ball = Kinetic energy + potential energy

When the ball finally hit's ground it's potential energy becomes zero thus final energy becomes

Equating both the energies and applying the given values we get

it is called kinetic energy