A 500 grams ball is thrown vertically upwards with a speed of 20 metres per seconds. what is the kinetic energy of the ball at the height of 5 metres?

Ek = 24.5 [J]

Explanation:

To solve this problem we must use the theorem of work and energy which tells us that potential energy is transformed into kinetic energy or vice versa.

In this way, the kinetic energy will be equal to the potential energy at each moment.

Ep = Ek

With the height and mass data, we can find the potential energy.

Ep =m*g*h

where:

Ep = potential energy [J] (energy in Joules)

m = mass = 500 [gr] = 0.5 [kg]

g = gravity acceleration = 9.81 [m/s²]

h = elevation = 5 [m]

Ep = 0.5*9.81*5

Ep = 24.5 [J]

So the kinetic energy is the same that the potential energy.

Ek =24.5 [J]