A 10.0-kg mass is placed on a 25.0o degree incline and friction keeps it from sliding

1. Nov 5, 2012

zedx

1. The problem statement, all variables and given/known data

A 10.0-kg mass is placed on a 25.0o degree incline and friction keeps it from sliding. The
coefficient of static friction in this case is 0.580, and the coefficient of sliding friction is
0.520. The mass is given a shove causing it to slide down the incline.

2. Relevant equations

What is the frictional
force while the mass is sliding?

3. The attempt at a solution

This is all I have so far, but I don't exactly understand it:

Frictional force while the mass is sliding = μmgcosθ = 0.52 X 10 X 9.8 X cos 25
= 46.19 N

I need a full step-by-step explanation, if possible. I'll also take any other information about the problem that may make it easier. Thank you.

2. Nov 5, 2012

Delphi51

Re: A 10.0-kg mass is placed on a 25.0o degree incline and friction keeps it from sli

You also need to find the downward, along the ramp force. It is the other component of mg, that is mg*sin(25). The net force along the ramp is this force minus the friction force.

I always draw the ramp, put the mass at the very top and draw the mg force vector straight down. Then separate that mg into the sum of a force along the ramp and perpendicular to the ramp. The perpendicular force is the normal force pulling the mass against the ramp surface.

3. Nov 5, 2012

Simon Bridge

Re: A 10.0-kg mass is placed on a 25.0o degree incline and friction keeps it from sli

Welcome to PF;
Draw a free-body diagram for the mass and you'll see how that relation was found.

4. Nov 5, 2012

zedx

Re: A 10.0-kg mass is placed on a 25.0o degree incline and friction keeps it from sli

I'll do all of the above. Thank you.

5. Nov 7, 2012

Simon Bridge

Re: A 10.0-kg mass is placed on a 25.0o degree incline and friction keeps it from sli

Cool! Let us know how you get on.