Friction and the Coefficents of Friction question

  • Thread starter emilypanthel
  • Start date
  • Tags
    Friction
In summary, we are given a horizontal force of 110 N to move a 35 kg box and need to calculate the coefficient of static friction. We can use the equation Ff=uFn and organize the given information to solve for the unknown coefficient. Additionally, we are given a system of blocks connected by strings and need to find the tensions and time before one block jams the pulley.
  • #1
emilypanthel
1
0

Homework Statement


so my question is; A horizontal force of 110 N (forward) is required to get a 35 kg box to start moving across a floor, Calculate the coefficent of static friction.
The equations i have been given are Ff=uFn
But I have just started this unit and am so confused. I don't even know where to start.


Homework Equations





The Attempt at a Solution

 
Physics news on Phys.org
  • #2
First, draw a free body diagram for the box - include all forces.
It may help to list what you know and what need to find (organize the info outside of the question).
 
  • #3
Floor is horizantal so normal force equals gravitational force. To break frictional force, applied force must equal it.
 
  • #4
1. Three blocks are tied to each other with
two pieces of string, one of which
passes over a frictionless pulley, as
shown. The coefficient of friction
between each block and the surface on
which it slides is 0.2. Just as the
system starts to move, the 3 kg and
6 kg blocks are each one metre away
from the pulley.

1.1Determine the tension in each of the strings.
1.2 How long before one of the blocks jams the pulley?
 

Attachments

  • Diagram....jpg
    Diagram....jpg
    15.7 KB · Views: 376
  • #5


I understand your confusion and I am here to help you understand the concept of friction and coefficients of friction. First, let's define friction - it is the force that resists the motion of one surface over another. In this case, it is the force that is preventing the box from moving across the floor.

The coefficient of static friction, denoted by μs, is a unitless value that represents the ratio of the maximum friction force to the normal force between two surfaces. In simpler terms, it is a measure of how difficult it is to move an object over a surface.

Now, let's use the equation you have been given, Ff = μFn, where Ff is the friction force, μ is the coefficient of friction, and Fn is the normal force. In this case, we know that the friction force is equal to the horizontal force of 110 N, and the normal force is equal to the weight of the box, which is given as 35 kg. So, we can rewrite the equation as 110 N = μ(35 kg x 9.8 m/s²). Simplifying, we get μ = 110 N / (35 kg x 9.8 m/s²) = 0.31.

Therefore, the coefficient of static friction between the box and the floor is 0.31. I hope this helps you understand the concept better. Remember, the coefficient of friction can vary depending on the materials and surfaces involved, so it is important to always use the correct values for accurate calculations.
 

1. What is friction?

Friction is a force that resists motion between two surfaces that are in contact with each other. It is caused by the irregularities on the surfaces and the interlocking of the molecules between the surfaces.

2. What is the coefficient of friction?

The coefficient of friction is a dimensionless value that represents the amount of friction between two surfaces. It is a ratio of the force required to move an object over a surface to the weight of the object.

3. How is the coefficient of friction measured?

The coefficient of friction can be measured using a device called a tribometer, which applies a known force to the surface and measures the resistance to motion. It can also be calculated by dividing the force of friction by the normal force acting on the object.

4. What factors affect the coefficient of friction?

The coefficient of friction can be affected by a variety of factors, including the types of surfaces in contact, the roughness or smoothness of the surfaces, the force pressing the surfaces together, and the presence of lubricants or other substances between the surfaces.

5. How does friction impact everyday life?

Friction plays a crucial role in our everyday lives. It allows us to walk, drive, and grip objects. It also helps to slow down and stop moving objects, making it essential for safety. However, excessive friction can also cause wear and tear on surfaces and machines, so it is important to understand and control friction in various situations.

Similar threads

  • Introductory Physics Homework Help
Replies
11
Views
1K
  • Introductory Physics Homework Help
Replies
18
Views
1K
  • Introductory Physics Homework Help
Replies
16
Views
1K
  • Introductory Physics Homework Help
Replies
20
Views
2K
  • Introductory Physics Homework Help
Replies
9
Views
959
  • Introductory Physics Homework Help
Replies
5
Views
4K
  • Introductory Physics Homework Help
Replies
7
Views
264
  • Introductory Physics Homework Help
Replies
8
Views
856
  • Introductory Physics Homework Help
Replies
6
Views
128
  • Introductory Physics Homework Help
Replies
7
Views
1K
Back
Top