Friction Experiment

The purpose of this experiment is to measure the friction force on the ball

Define average velocity:

Define Mass:

Define Acceleration:

Define Newton’s second law:

EXPLANATION

EQUIPMENT

In this experiment we will measure the friction acting on a small rubber ball as it rolls over a piece of poster board. To do this experiment you will need to measure in centimeters. Most rulers that are found in the stores have inches on one side and centimeters on the other (12 inches one side and 31 centimeters on the other on the other side). Remember 1 meter is 100 centimeters. You will also need a stopwatch, a piece of poster board, and a small rubber ball.

SETTING UP THE TRACK

Now cut the poster board into three strips. One strip will form the ramp, and the other two will form the horizontal run. You may need some stiff cardboard or a board to reinforce the ramp. Tape the horizontal run to a table (or the floor) so that it will be flat. Your set-up should resemble the diagram on the next page.

Once you have taped down your board you will have to divide it into sections. Section 1 will be from 1 to 2. Section 2 will be from 2 to 3.

Point A will be in the middle of section 1. Point B will be in the middle of section 2.

CALCULATIONS OVERVIEW

In order to find the force of friction it is necessary to first calculate the acceleration of the ball. In order to do this:

1)calculate the average velocity for section 1 and assume this is the velocity for point A

2)calculate the average velocity for section 2 and assume this is the velocity for point B

3)measure the time it takes the ball to roll from A to B

4)

PROCEEDURE & CALCULATIONS

First you must choose a starting point (H1 for example) and roll the ball from this point

1) Calculate Average velocity section 1 & V point A

Roll the ball from the starting point and measure and the time it takes for the ball to roll from point 1 to point 2 call this timeT12 therefore T12 =______sec

Calculate V average for section1:

V average section1 = 1m/T12 = _________m/s

Assume V average section 1 = V point A

Therefore V point A = _______m/s

2) Calculate Average Velocity section 2 & V point B

Roll the ball from the starting point and measure and the time it takes to roll from point 2 to point 3 call this time T23 therefore T23 =______sec

Calculate V average for section 2:

V average for section 2 = 1m/T23=________m/s

Assume V average section 2 = V point B

Therefore V point B = _______m/s

3) Acceleration between point A and B

Roll the ball from the starting point and measure the time it takes for the ball to roll from point A to point B therefore TAB =______sec

Calculate Acceleration

Acceleration = (V point B – V point A)/ TAB = ________m/s/s

Repeat steps 1 2 & 3 for another set of data

1) Calculate Average velocity section 1 & V point A

Roll the ball from the starting point and measure and the time it takes for the ball to roll from point 1 to point 2 call this timeT12 therefore T12 =______sec

Calculate V average for section1:

V average section1 = 1m/T12 = _________m/s

Assume V average section 1 = V point A

Therefore V point A = _______m/s

2) Calculate Average Velocity section 2 & V point B

Roll the ball from the starting point and measure and the time it takes to roll from point 2 to point 3 call this time T23 therefore T23 =______sec

Calculate V average for section 2:

V average for section 2 = 1m/T23=________m/s

Assume V average section 2 = V point B

Therefore V point B = _______m/s

3) Acceleration between point A and B

Roll the ball from the starting point and measure the time it takes for the ball to roll from point A to point B therefore TAB =______sec

Calculate Acceleration

Acceleration = (V point B – V point A)/ TAB = ________m/s/s

COMPARE THE TWO SETS OF DATA

Are the close?

Are they accurate?

CALCULATEM THE FORCE DUE TO FRICTION

Assume that the rubber ball weighs .1kg.

Force = Mass*Acceleration = _________________