Question

HELPPPPP!!!! PLZZZZZZZ!!!!

EXPLAIN PLEASE I DONT UNDERSTAND
A runner has a speed of 25 m/s. They see the finish line and speed up to 30 m/s. This happens in 5 seconds. If the runner has a mass of 75 kg, with what force did the runner cross the finish line? Show all work to receive full credit.

I know the answer is 75N but I don't know how to get 75N

Answer 1

Given parameters:

Initial velocity = 25m/s

Final velocity = 30m/s

Time = 5m/s

Mass of runner = 75kg

Unknown:

Force to finish the race = ?

Solution:

Force is defined as a pull or push on a body. According to Newton's first law, we can mathematically express force as the product of mass and acceleration;

Force = mass x acceleration

But we know that acceleration is the change in velocity with time, so;

Acceleration =
`(Final velocity - Initial velocity)/(time)`

So, force;

Force = mass x
`(Final velocity - Initial velocity)/(time)`

Input the parameters and solve;

Force = 75 x
`(30 -25)/(5)` = 75N

The runner crosses the line with a force of 75N