Finding Applied Force from Coefficient of Friciton and mass

Click For Summary
SUMMARY

The discussion focuses on calculating the applied force required to prevent a 3.0 kg wooden box from sliding down a wall, given a coefficient of static friction of 0.60. The user correctly applies the frictional force formula, FF = uFn, resulting in a calculated frictional force of 17.658 N. The conversation highlights the importance of understanding the balance of vertical forces, emphasizing that the upward frictional force must equal the downward gravitational force to maintain equilibrium.

PREREQUISITES
  • Understanding of static friction and its coefficient
  • Knowledge of Newton's second law (F = ma)
  • Familiarity with force balance concepts in physics
  • Basic calculations involving gravitational force (g = 9.81 m/s²)
NEXT STEPS
  • Study the concept of normal force in static friction scenarios
  • Learn about dynamic friction and its differences from static friction
  • Explore applications of Newton's laws in real-world problems
  • Investigate the effects of varying coefficients of friction on force calculations
USEFUL FOR

Students studying physics, particularly those focusing on mechanics, as well as educators seeking to clarify concepts related to friction and force balance.

jmcpherson82
Messages
2
Reaction score
0
So I've been stuck on this type of question, please help!

You are pushing horizontally on a 3.0 kg box of wood, pressing against a wall. If the coefficient of static friction is 0.60, how much force must you exert on the block to prevent it from sliding down?


Homework Statement


What is the force applied to keep the box from sliding down?

m= 3.0kg
u= o.60
g=9.81


Homework Equations



FF=uFn
Fnet = ma


The Attempt at a Solution



I tried to use the equation FF=uFn:

FF = .6(3)(9.81)
FF=17.658 N


Am I doing this correct?
 
Physics news on Phys.org
Hi jmcpherson82. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif


The vertical forces must balance. The upward force due to friction = 0.6 Fn
 
Last edited by a moderator:
So how would I find Fnet without acceleration? Because then I can't do the equation Fnet = ma
 
jmcpherson82 said:
So how would I find Fnet without acceleration? Because then I can't do the equation Fnet = ma

Fnet=0
EDIT: Oh, N.O.'s talking about normal force not net force.
 
jmcpherson82 said:
So how would I find Fnet without acceleration? Because then I can't do the equation Fnet = ma
The upward force = the downward force

The upward force is due to friction.
 

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?
View full post »

Similar threads

Coefficient of Friction when Normal Force is Reduced [HS]
  • · Replies 5 ·
Replies
5
Views
2K
How to find the Coefficient of friction from Fn and Ff Graph
  • · Replies 2 ·
Replies
2
Views
10K
Determining Coefficient of Friction for Two Boxes with Applied Force
  • · Replies 14 ·
Replies
14
Views
2K
Complex Kinematics and Dynamics
  • · Replies 8 ·
Replies
8
Views
2K
How do i find the coefficient of static friction?
  • · Replies 2 ·
Replies
2
Views
2K
Coefficient of kinetic friction of a block sliding across the ceiling
  • · Replies 7 ·
Replies
7
Views
1K
Frictional Force Problem: Solve with 25kg & 0.36 Coefficient
  • · Replies 6 ·
Replies
6
Views
2K
Dynamics ramp and friction. Finding angle?
  • · Replies 4 ·
Replies
4
Views
2K
Complex Kinematics and Dynamics
  • · Replies 7 ·
Replies
7
Views
2K
How Do I Determine Force of Static Friction on a Rolling Car
  • · Replies 15 ·
Replies
15
Views
2K