Physics 1
Dynamics Lab Activity



To investigate the nature of friction


Friction is a very common (and sometimes troublesome) force. How does it work? What does the force of friction depend on? You will probably not be surprised to know that some aspects of the behavior of friction are quite surprising.


friction block

spring scale

set of masses

various surfaces


Part 1. Friction and the Normal Force -

If you are dragging a box across the floor, and somebody jumps onto to it, the box will be harder to pull, right? The added weight of the person must have increased the friction force between the box and the floor.

[Diagram of Experimental Setup]Investigate this relationship by measuring the friction force between the block and the table as you add weight to the block. (The friction force between the block and the table equals the force that you have to exert to move the block at constant velocity - Newton's First Law.) Make a data table to display your measurements and results. What do you conclude?

Part 2. Friction & Surface Area -

How does friction depend on surface area? You can investigate this by turning the friction block to different sides (with different areas) and measuring the friction force. Report your data, results, and conclusions below.

Part 3 - Friction and Speed -

How does the friction force between two surfaces depend on their relative speed? Put your data, results, and conclusions in the space below.


last update November 22, 1996 by JL Stanbrough (Questions, comments, and suggestions are welcome at