SAIL into STEM

Friction using Car and Ramp and the

Engineering Design Cycle

Learning Goals

Use technology to measure and describe forces acting on a car in motion.

Define friction.Distinguish among various types of friction.

Design a sail car that will slow down or speed up a car undergoing friction

Explain applications of friction.

Friction Friction is a force that resists the

motion of objects or surfaces. Many kinds

of friction exist.

Friction

Defining a “system”First we need to see how a car responds to unbalanced forces and identify the types of friction.

Set up your equipment and let’s see what we variables we can control.

Setting up the experiment

Friction and two surfaces Friction depends on both of the surfaces in

contact.

When the hockey puck slides on ice, a thin layer of water between the rubber and the ice allows the puck to slide easily.

Friction and energy

Each time two moving surfaces touch each other, tiny bits of material are broken off by friction.

Breaking off bits of material uses energy.

Identifying friction forces

Friction is a force, measured in newtons just like any other force.

Sliding friction is a force that resists the motion of an object moving across a surface.

Identifying friction forces

Collect Data

Create the “Sail Car”

Make a hypothesis

If the sail is affected by air friction, then the car’s speed will:

a) slow down by ______ %

b) speed up by ______ %

c) stay the same

Collect Data for “Sail Car”

Analyze any % change in Average Speed due to Air

Friction% increase = Trial 1 – Trial 2 x 100%

Trial 1

% decrease = Trial 2 – Trial 1 x 100% Trial 1

Friction and energy

Friction changes energy of motion into heat energy.

Reducing the force of friction

Unless a force is constantly applied, friction will slow all motion to a stop eventually.

It is impossible to completely get rid of friction, but it can be reduced.

Using friction

Friction is also important to anyone driving a car.

Grooved tire treads allow space for water to be channeled away from the road-tire contact point, allowing for MORE friction in wet conditions.

Using friction Shoes are designed

to increase the friction between their soles and the ground.

How do you think these shoes increase friction?

Modify your “Sail Car”

Use materials to make modifications to the sail.

Increase your friction by 10% or decrease your friction by 10%