Register to reply

Can someone help me with this static friction problem?

by shaggyace
Tags: friction, static
Share this thread:
Mar12-12, 03:51 PM
P: 11
1. The problem statement, all variables and given/known data

A 45-kg crate is placed on an inclined ramp. When the angle the ramp makes with the horizontal is increased to 24 degrees , the crate begins to slide downward. What is the coefficient of static friction between the crate and the ramp?

2. Relevant equations



3. The attempt at a solution

I started by drawing a free body diagram. My weight came out to be -441 N. I have the angle of my weight at 24 degrees. The normal force at mgcos24, for which I got 187N. mgsin24 came out to be 399N which is also the static friction force. Then I just substituted into the static friction equation and my coefficient of static friction came out to be 2.13. I entered this into the homework problem which we do online and it is wrong. Did I miss a step? What did I do wrong?
Phys.Org News Partner Science news on
Experts defend operational earthquake forecasting, counter critiques
EU urged to convert TV frequencies to mobile broadband
Sierra Nevada freshwater runoff could drop 26 percent by 2100
Mar12-12, 04:01 PM
P: 157
Your values for mgcos24 and mgsin24 are incorrect. Your calculator appears to be in radian mode.
Mar12-12, 04:06 PM
P: 297
The applied formula is right.The math is wrong.

the weight u calculated using m as 450 and g as 9.8 (all in SI units) is right as 441 N.

As u said normal force is mgcos24.
and mgsin24 as component of weight parallel to inclined plane.

However, the calculated values are not right.

Hint(for angles less than 45 degrees cos x is always greater the sin x.

However, here your mgcos24 is less than mgsin24)

Mar12-12, 04:08 PM
P: 11
Can someone help me with this static friction problem?

Wow, thanks a lot Calc class, lol.
Got the answer, thanks for your help guys

Register to reply

Related Discussions
Friction problem with banked curve given static friction coefficient Introductory Physics Homework 3
Static friction problem Introductory Physics Homework 6
Static Friction Problem Introductory Physics Homework 10
SHM - problem with static friction Introductory Physics Homework 3
A Static friction problem Introductory Physics Homework 4