How Much Force Stopped the Diver Underwater?

[plqaokws]

Homework Statement

A 50 kg diver enters the water moving at 4 m/s. He eventually comes to a stop 3 meters below the water surface. What amount force brought the diver to a stop?

Homework Equations

Is the acceleration -9.8 m/s^2?
Then, would you use F = ma to find the net force?

The Attempt at a Solution

i tried to do F = (50 kg)(-9.8 m/s^2) but i don't think that's right...

Thank you.

 

[FedEx]

Homework Statement

A 50 kg diver enters the water moving at 4 m/s. He eventually comes to a stop 3 meters below the water surface. What amount force brought the diver to a stop?

Homework Equations

Is the acceleration -9.8 m/s^2?
Then, would you use F = ma to find the net force?

The Attempt at a Solution

i tried to do F = (50 kg)(-9.8 m/s^2) but i don't think that's right...

Thank you.

This will not work as the acc is not equal to -g. You have the velocity when the body touches the water surface. This is the initial velocity. Now the final velocity is zero.And the distance is 3m. So by v^2-u^2=2ad.You can find a, and then you can apply f=ma.Here v is the final velocity and u is the initial velocity.