Exercise 1: Planning your experiment
In this lab you will be exploring the science of friction. The goal of the following experiments are to determine the coefficient of static and kinetic friction between your shoe and an inclined surface of your choice (i.e. measure the mu of your shoe).
There are several common ways of making this type of measurement, and today you will be using the setup described in parts c) and d) of the Free-body diagrams: Warm-Up Exercise. You will look at two cases:
1. When your shoe is just about to slide, where any greater angle of the ramp will result in the shoe accelerating down the ramp.
2. When your shoe accelerates at a constant rate down a ramp with the same angle found in Case 1.
Before you continue, collect the following:
- Inclined plane/ramp for which the angle can be adjusted. Suggestions: a long piece of cardboard works great to make a ramp, or a coffee table that you can tilt, a whiteboard, anything smooth and flat that can be tilted and has a length of at least 40cm, the longer it is the more accurate your measurement results.
- Protractor
- One shoe, or your McMaster standard calculator.
- Measuring tape
Scenario 1: Your shoe is on a flat surface and is slowly inclined.
For this scenario answer the following:
Exercise 1.1 (1 mark)
Draw the FBD for the forces that are acting on your shoe right before it starts sliding but is still stationary, and make sure you properly label the forces. Define your axes to be parallel and perpendicular to the ramp. Take the direction down the ramp to be the positive x-direction, while upwards and out of the ramp will be the positive y-direction. Pick the correct option(s) directly on Crowdmark.
Exercise 1.2 (1 mark)
Write an equation for the sum of the forces acting on your shoe in the direction parallel to the ramp. Your equation should look like this:
[sum of all forces] = ma = 0 N
where [sum of all forces] is a list of all of the forces acting on your shoe in the parallel x-direction. Make sure you include the correct sign for your forces. You may wish to refer to one of the free-body diagrams in the Free-body diagrams: Warm up exercises. Pick the correct option(s) directly on Crowdmark.
Scenario 2: Your shoe is on an angled flat surface and accelerates downwards.
For this scenario answer the following:
Exercises 1.3 (1 mark)
Draw the FBD for the forces acting on your shoe when it is sliding down the ramp. Remember: The length of the vector corresponds to the magnitude of the force. Pick the correct option(s) directly on Crowdmark.
Exercises 1.4 (1 mark)
Write an equation for the net force acting on your object in the parallel direction. Your equation should look like this:
[sum of all forces] = ma
where [sum of all forces] is a list of all of the forces acting on your shoe in the parallel direction. Pick the correct option(s) directly on Crowdmark.
Exercises 1.5 (1 mark)
How does the equation in (1.4) differ from the equation in (1.2)? Pick the correct option(s) directly on Crowdmark.
Think about it:
In this exercise, we looked at the net force in the direction parallel to the ramp. What about the net force in the direction perpendicular to the ramp? Taking the time to think about this will be helpful for the upcoming exercises.
Before you continue!
Before continuing, be sure you have completed Exercises 1.1 – 1.5, which will be graded and submitted through Crowdmark.
