# What kind of strength does a 50 kg student develop in a 30-meter run if he runs this distance in 5 seconds?

**What kind of strength does a 50 kg student develop in a 30-meter run if he runs this distance in 5 seconds? Is the calculation to be made on the assumption that the student is moving all the time with constant acceleration, without encountering air resistance?**

The force that a student develops while running is calculated according to Newton’s second law:

F = m * a, where m is the student’s mass (m = 50 kg), a is the student’s constant acceleration.

We express the acceleration from the formula (the initial speed is assumed to be zero):

S = a * t ^ 2/2, where S is the distance that the student has run (S = 30 m), t is the running time (t = 5 s).

a = 2S / t ^ 2.

F = m * 2S / t ^ 2 = 50 * 2 * 30/5 ^ 2 = 120 N.

Answer: The student develops a force of 120 N.