The body was thrown from the surface of the earth vertically upwards at a speed of 72 km / h.

The body was thrown from the surface of the earth vertically upwards at a speed of 72 km / h. What is the maximum height it can reach?

Given:

u0 = 72 kilometers per hour – the initial speed of a body thrown vertically upward;

a = 10 meters per second squared – the acceleration of gravity.

It is required to determine h (meter) – the maximum height that the body can reach.

Let’s convert the units of measurement of speed to the SI system:

u0 = 72 km / h = 72 * 10/36 = 20 m / s.

Since, according to the condition of the problem, air resistance can be ignored, then, according to the law of conservation of energy:

Ekin (at the surface of the earth) = Epot (at the maximum height);

m * u ^ 2/2 = m * a * h, where m is body weight;

u ^ 2/2 = a * h;

h = u ^ 2 / (2 * a) = 20 ^ 2 / (2 * 10) = 400/20 = 40/2 = 20 meters.

Answer: the body can reach a maximum height of 20 meters.