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Attached.
Lab 4 – Friction Forces
Name: ____________________________________________________
Objectives
1. To understand the effect of the forces of friction during the motion of objects.
2. To explore experimentally the Newton’s Second Law (relation between force, mass and
acceleration)
In your responses use scientific terms such as, constant, increase, decrease, velocity, force, mass
and acceleration.
Click on the link below to open the simulation:
http://phet.colorado.edu/en/simulation/ramp-forces-and-motion
.
You will be starting with a crate that has a mass of 100 kg and a coefficient of sliding friction of
0.3 and a coefficient of static friction of 0.5.
1. Draw the Free Body Diagram before you apply any force.
Normal force
WWeight (100g)
2. Add 10 N of applied force, and push the
free body diagram showing all the forces.
button and record what happens. Include a
No motion.
Fn
Applied force
Friction force
Fg
3. Add 100 N of applied force and push the
button. What changed?
No motion again. But the friction force was increased as increase of the applied force.
4. Use the friction equation to calculate how much force would be required to get it moving.
Show your work here. What happened? How did you fix the problem to get it moving?
Applying 𝐅 = 𝛍𝐑
𝐅 = 𝟎. 𝟓(𝟏𝟎𝟎𝐠) = 𝟎. 𝟓(𝟏𝟎𝟎)(𝟗. 𝟖) = 𝟒𝟗𝟎 𝐍
After applying 490N, no motion. The reason for that is the friction force still equal to the
applied force. To move the mass the applied force should be larger than this force.
Therefore, the problem was solved by increasing the applied force little than 490N.
5. What happened as the crate moved up the ram...