Pre-Lab 5B: Friction

Purpose

• Friction is always present. • Sometimes we want friction. • For example, friction between tires and the road

allows a car to be steered safely and maintain its direction when moving.

• Other times we want to reduce friction. Putting oil on a bicycle chain allows it to work more efficiently with the gears.

• This investigation explores different effects of friction.

Key Question

• How does friction affect motion?

Background

Define:• Friction• List three types of friction• What unit is friction measured in?

Drawing

Draw this:

Procedure

You will need, in addition to the ramp, car and photogates:

sled (not car!)

rubber band (don’t break it)

steel ball (do not loose it!!)

plastic knife

paper plate

tape: leave at the front desk

Section 1:

you will be measuring air friction on the car

This will be the control

What is a control?

Measure distance to the closest millimeter: use 3 sigfigs!!

How do you calculate average?

Step 4: what do you include and where does it go specifically?

Section 2:

Create a sail car: demo

Section 3:

Formally Hypothesize the outcome compared to the control experiment:

use: IF…THEN…BECAUSE

Section 4:

Test the hypothesis

Section 7:

Rolling and sliding friction:

ramp is horizontal: exactly!!!

use the rubber band in an X on the launch stand: demo

use the SLED, not the car

no steel marble

READ!

Section 8:

record your sled data in sliding friction data chart

repeat format for sled, but now use the car to get the rolling data

record in rolling friction data chart

Post Lab 5 B: Friction

Purpose

• Friction is always present, even when not moving: static friction

• Sometimes we want friction. • For example, friction between tires and the road

allows a car to be steered safely and maintain its direction when moving.

• Other times we want to reduce friction. Putting oil on a bicycle chain allows it to work more efficiently with the gears.

• This investigation explores different effects of friction.

Key Question

• How does friction affect motion?

Background

Define:

friction

list three types of friction

what unit is friction measured in?

How did air friction affect the car’s motion?

Where did this friction come from?

How would you use this knowledge to design a car?

Where else did friction come from?

In terms of the accelerations, where they positive or negative?

Which decelerated more: car or sled? why?

How could you decrease/increase the sliding friction?

How could you decrease/increase the rolling friction?

Of the three types of friction (?), which had the greatest/least effect on motion?