Lab 11 Dynamics Lab Report

Grade 11 Dynamics
Lab Report

Friction

SPH3U1-02 Williams. C.

By----James & Hao Feng & Henry Zhang

Purpose:
By measuring the friction and μ of a container and change different variables including mass, surface and gradient, get causes of the change of friction and μ.

Materials:
A container
Three Pen bag in different mass
A rough wood board
A clean desk
Rulers
Thrust meter.

Steps
Prepare the materials that we gonna use. (Thrust meter; Pen bag; container; a board, ruler)
Measure the mass and the Gravity of the stuffs that we are going to use. (Pen bag and container)
Make sure the degree of the included angle between the table and
board)
Calculate the length of the board.
Calculate the distance which the container is gonna move.

One
Use the Thrust meter to pull the empty container.
Use the Thrust meter to pull the container with pen bag. (Do this for 3 times because there are three pen bags in different mass and it can decrease the error.)

Two
Use the Thrust meter to pull the empty container on the slide (board) slowly and write down the number on the Thrust meter when it starts to move.
Write down the number on the Thrust meter when the empty container is moving.
And then, put the pen bag in the container and do the last step again.
The final step should be changing the gradient and does the steps above again.

Determine the frictions on a level
Static Friction

Static frictional forces from the interlocking of the irregularities of two surfaces will increase to prevent any relative motion up until some limit where motion occurs. It is that threshold of motion which is characterized by the coefficient of static friction. The coefficient of static friction is typically larger than the coefficient of kinetic friction.

m1=container

m1=380g m2=170g m3=300g m4=100g

M(g)
Fg(N)
Ffs(N) μs m1
380
3.724
1
0.269 m1+m2 550
5.39
1.3
0.241
m1+m2+m3+m4
950
9.31
2.3
0.247

Change surface and do the steps above again:

M(g)
Fg(N)
Ffs(N) μs m1
380
3.724
1.4
0.376 m1+m2 550
5.39
2.1
0.39
m1+m2+m3+m4
950
9.31
3.9
0.419

Kinetic Friction:

When two surfaces are moving with respect to one another, the frictional resistance is almost constant over a wide range of low speeds, and in the standard model of friction the frictional force is described by the relationship below.
The coefficient is typically less than the coefficient of static friction, reflecting the common experience that it is easier to keep something in motion across a horizontal surface than to start it in motion from rest.

m1=container

m1=380g m2=170g m3=300g m4=100g

M(g)
Fg(N)
Ffk(N) μk Ff m1 380
3.724
0.8
0.215
0.8 m1+m2 550
5.39
1.1
0.204
1.1 m1+m2+m3+m4 950
9.31
2
0.215
2

Change surface and do the steps above again:

M(g)
Fg(N)
Ffk(N) μk Ff m1 380
3.724
1.1
0.295
1.1 m1+m2 550
5.39
1.7
0.315
1.7 m1+m2+m3+m4 950
9.31
3.2
0.332
3.2

Determine the frictions on a
slide

Though representing a simplistic view of friction, agrees fairly well with the results of simple experiments with wooden blocks on wooden inclines. The experimental procedure described below equates the vector component of the weight down the incline to the coefficient of friction times the normal force produced by the weight on the incline.

For determining, we measure the values of the container that we use and it’s information have been shown in the form below when it is empty:

The Mass Of The Container
380g
The Gravity Of The Container
3.7N
Static Friction
2.7N
Kinetic Friction 2.4N

According to the information above, we start our first experiment

In the first experiment, we are going to use only one pen bag in the container. Before we put it in, we gotta measure the Mass and Fg.

The Mass Of The Pen Bag
170g
T he Fg Of The Pen Bag
1.67N

And then, we put it in the container and put them on the slide and we use the Thrust meter to pull the container up on the slide. According to the measuring, the in formation we find can be shown below:

The Gradient
17.97°
The Total Mass
550g
The Total Gravity
5.37N
The distance we pull 23cm Static Friction
4.6N
Kinetic Friction 4.3N
Now, let’s change the GRADIENT.
The Gradient
22.34°
The Total Mass
550g
The Total Gravity
5.37N
The distance we pull 23cm Static Friction
5.1N
Kinetic Friction 4.7N

Conclusion:
There are three factors which can affect the friction and μ of an object. When the surface is not change, if mass of the object became bigger, the friction will become bigger. When the mass of an object do not change, the surface is rough than before, friction will also become bigger..
When both of mass and surface do not change, if gradient become bigger, the friction will also become bigger. Mass, surface of object and gradient are three factors which can affect the friction of an object.