1.Put a wooden black on the table, tie a string to the block and connect to water cup over a pulley at the end of the track.And then, we put water to the cup patiently until the block finally starts to slide to edge of table.Record the mass of the cup and water required to get block to start to move.And we add 3 times wooden block and record them to record their mass of wooden block and mass of water.
The record :
After this, we plug all data into computer to create the graph:
So that, we can the coefficient of static friction between table and block is
0.2188.
2.drag the block in constant speed by motion sensor which is connected to the block, and we get the graph from Labpro:
And this graph gives us the average kinetic friction force between the block and the track.
After we measure those blocks' mass, we create the table to record mass of block and normal force.
mass(kg) normal force(N) friction(N)
- 0.11 1.078 0.3177
- 0.236 2.3131 0.6187
- 0.295 2.89 0.852
- 0.45 4.411 1.3
we model sliding friction as being proportional to the normal force, and speed of the moving object. That is, we create a function:
Fkinetic=K*N=>K=Fkinetic/N
we get the number K is 0.2947.
3.We make a slope with the metal track and put the motion sensor at the bottom of the track, and then let a wooden block to slide down to bottom from top.And we can record the acceleration with computer and sensor, show in picture:
from this graph, we are able to apply the equation to get net force:
and the net force is equal to sin(a)*mg-Ffriction so we can get:
=>
divide the m
=>
the a=0.8527m/s^2,angle a=20degrees, so we get k=0.2807
4.we make a slope, connect the block which is on slope to a mass over pulley, and make the angle between slope and horizontal table to be just make the mass can drag the block to move.
And now, we know the mass is 0.15kg,angle is 21.5degree,block is 160kg, and acceleration is 0.545m/s^2 with measuring.
we create a equation:
and we can get k is 0.5539
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