(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

You and your friend Peter are putting new shingles on a roof pitched at 22 degree . You're sitting on the very top of the roof when Peter, who is at the edge of the roof directly below you, 5.0 m away, asks you for the box of nails. Rather than carry the 2.5 kg box of nails down to Peter, you decide to give the box a push and have it slide down to him.

If the coefficient of kinetic friction between the box and the roof is 0.53, with what speed should you push the box to have it gently come to rest right at the edge of the roof?

2. Relevant equations

Vf^2=Vi^2+2*a*delta s

F=ma

3. The attempt at a solution

First found the length of the roof by assuming that the height was 5m and angle 22* i found the length to be 13.3475meters using trig....sin(22)=5m/roof length

then i did the force calculations to find Fnet then find the acceleration:

9.8cos(22)*2.5kg=22.71N

9.8cos(22)*2.5kg*.53= -12.039N

Fnet=22.71-12.039N

Fnet=10.671N

Then solved for the acceleration:

F=ma

10.671N=2.5kg * a

a=4.2684m/s^2

then i plugged those values into this equation to find Vi

Vf^2=Vi^2+2*a*delta s

0=Vi^2 + 2 * (4.2684m/s^2) * (13.3475m)

Vi=10.67m/s

is this correct? thank you!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Nails going down the side of the roof

**Physics Forums | Science Articles, Homework Help, Discussion**