Frictional Force of a Crate of Potatoes: 13 kg, 40° incline

AI Thread Summary
To find the frictional force on a 13 kg crate of potatoes on a 40° incline, the static friction must be calculated while considering the crate is at rest. The maximum static friction is not necessarily the actual frictional force; instead, it should be determined by analyzing the forces in equilibrium. The relevant forces include weight, friction, and normal force, with weight acting downward, friction opposing motion, and normal force acting perpendicular to the incline. By applying the equation for static friction and ensuring the net force equals zero, the correct frictional force can be derived. Understanding the components of forces along the incline is crucial for solving the problem accurately.
lalahelp
Messages
74
Reaction score
0

Homework Statement


A crate of potatoes of mass 13.0 kg is on a ramp with angle of incline 40° to the horizontal. The coefficients of friction are μs = 0.78 and μk = 0.43. Find the frictional force (magnitude) on the crate if the crate is at rest.



Homework Equations


F=ma
Ff=μmgcosα


The Attempt at a Solution



Ff=.78*13*9.81*cos40
=76.2 N


Why is my answer wrong?
 
Physics news on Phys.org
You assumed that the static friction would be equal to its maximum possible value (μN). Instead, solve for the value of static friction considering that the crate is in equilibrium.
 
What equation would I use to do that?
 
lalahelp said:
what equation would i use to do that?
The net force is zero.
 
I don't understand it still
 
lalahelp said:
I don't understand it still
What forces act on the crate?
 
the mass and friction
 
lalahelp said:
the mass and friction
The weight, the friction, and the normal force. What direction does each act?
 
the weights acts straight down, friction to the right, and normal force up
 
  • #10
lalahelp said:
the weights acts straight down, friction to the right, and normal force up
Consider force components parallel to the incline and apply ΣF = 0.
 
  • #11
Ok thank you I got it !
 

Similar threads

What Is the Coefficient of Kinetic Friction Between the Ramp and the Crate?
Replies
6
Views
2K
Direction of a rope with a ball inside an accelerating box
Replies
5
Views
1K
Help with finding Normal Force of inclined plane
Replies
1
Views
3K
Crate pushed up an inclined plane
Replies
6
Views
6K
Friction Problem of a Crate Sliding Down a Ramp
Replies
4
Views
3K
Frictional Forces on a Wooden Crate with External Forces
Replies
1
Views
1K
Calculating Coefficient of Friction for a Crate on an Inclined Surface
Replies
2
Views
3K
Work done by the force of a man on a crate of 80N
Replies
14
Views
6K
How Much Force to Slide a Crate with Friction?
Replies
10
Views
2K
Why Does Cos(30) Calculate the Correct Frictional Force on a Sliding Crate?
Replies
2
Views
2K

Hot Threads

Recent Insights

Back
Top