Forces, Forces Everywhere
An investigation of frictional forces
around us
Forces
• Newton’s 2nd law: F=m*a
– Weight is an example of Force
– Gravity is an example of Acceleration
• Forces can be described by the direction in
which the acceleration acts
• Forces acting on surfaces
– Normal Force
“Nonconservative” Forces
• Friction
– Proportional to the normal force
– Exists for motionless and moving objects.
– Ff=μN
• Drag
– Proportional to velocity of fluid or object
– Fd=(½)ρv2CdA
• Density, velocity, drag coefficient, area
Purpose
• We will experiment with friction by examining
the force needed to move two surfaces past
each other, and analyze the force-position
data to calculate frictional coefficient(s).
Hypothesis
**Think about these questions**
Will the roughness of the wheels and sliding
surface (floor) have an effect on the force
required to move the car?
How are we comparing surface roughness?