How Does Friction Affect Falling Objects?

[hybridized]

Homework Statement

A construction worker at the top of a ladder drops her 250 g hard hat from a height of 22m. When it reaches the ground it is traveling at 9.0 m/s. What was the average fore of friction as it fell.

Homework Equations

Stuck here...

The Attempt at a Solution

Can't figure out what equations to use... Tried finding t, then using ft=mv and solving for t, but that does work.

 

[Xisune]

Use the work energy theorem.

 

[hybridized]

Use the work energy theorem.

Would you mind explaining buddy, kinda lost...

 

[Xisune]

W = ΔE_k + ΔE_p

W is work due to friction.
ΔE_k is the change in kinetic energy.
ΔE_p is the change in gravitational potential energy.

In this case, the hat gains kinetic energy but loses potential energy, so ΔE_k is positive, and ΔE_p is negative.

 

[hybridized]

KK I got that, but how would I go on to finding the force of friction?

 

[Xisune]

W = F x d, you know what d is.

 

[hybridized]

O I see now, so solving for F would give you the average force. True, thanks buddy mind taking a look at my other thread? Title is Momentum + Energy :)