+
ward
'
s
science
Page 5
6. Would the coefficient of friction change if surface area was kept the same and mass was increased? Explain your answer.
No, the force of friction would increase due to increased mass, but normal force would increase proportionally leading
to zero change in coefficient of friction.
7. If you increased the surface area of the "friction block" but kept the mass the same would the coefficient of friction change?
Explain your answer.
Most students will say that force of friction and coefficient of friction will change due to perceived life experience (width of
bike tires vs. car tires, etc.) but looking strictly at the friction formula, surface area is not included! So, no.
What would the free-body diagram of a stationary shoe look like? How about the shoe of a person walking forward?
Label the forces (do not assign numbers and don't forget tic-marks!).
Stationary shoe Shoe of person walking.
Both are the same!
Claim-Evidence-Reasoning: (CER) Shoe Bottoms
Teacher Key (continued)
