Safe Parking on Icy Days: Calculating Friction

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SUMMARY

The discussion centers on determining the safety of parking on icy driveways with varying inclines. The driveways in question have inclines of 13°, 8°, and 5°, with a coefficient of static friction of 0.15 between tire rubber and ice. Through calculations involving the forces acting on the car, it is established that only driveways with inclines less than or equal to 8.6° are safe for parking. Therefore, Ralph's (8°) and Bonnie's (5°) driveways are safe, while the 13° incline is not.

PREREQUISITES
  • Understanding of static friction and its coefficient
  • Basic knowledge of forces and inclines in physics
  • Ability to manipulate trigonometric functions
  • Familiarity with Newton's laws of motion
NEXT STEPS
  • Study the concept of static friction in detail
  • Learn about the forces acting on objects on inclined planes
  • Explore trigonometric applications in physics problems
  • Investigate real-world applications of friction in automotive safety
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Students studying physics, particularly those focusing on mechanics, as well as anyone interested in understanding the implications of friction on vehicle safety in icy conditions.

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Homework Statement


On an icy day, you worry about parking your car in your driveway, which has an incline of 13°. Your neighbor Ralph’s
driveway has an incline of 8°, and Bonnie’s driveway across the street has one of 5°. The coefficient of static friction
between tire rubber and ice is 0.15. Which driveway(s) will be safe to park in?

Homework Equations


Force of friction=F*u

The Attempt at a Solution


How can we know 'F' without knowning the mass of car?
 
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Just let mass=m, and leave it in the equations. When comparing the components of the forces in the horizontal direction, the masses will cancel.
 
Here is what I just did...

Sum of Forces in horz direction,
F_f*cos@-F_n*cos(90-@)=0
Since F_f=u*F_n
0=0.15*F_n*cos@-F_n*cos(90-@)
Divide by F_n, solve for @ to be 8.6 degrees. So both Ralph's and Bonnie's driveways will be ok?
 

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