A projectile of mass 0.50 kg is fired with an initial speed of 10 m/s at an angle of 60 degrees above the horizontal. The potential energy of the projectile-Earth system when the projectile is at its highest point (relative to the potential energy when the projectile is at ground level) is:

 U=18.75 J

Explanation:

given that

Mass ,m = 0.5 kg

Initial velocity , u= 10 m/s

angle, θ = 60°

The maximum height in the projectile motion h is given as follows

h=3.75 m

The potential energy is given as

U = m g h

U= 0.5 x 10 x 3.75 J

U=18.75 J

Therefore the potential energy at the highest point will be 18.75 J.