AP Physics Problem: Find Height on Icy Hill w/ 40km/h & 0.153 FK

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SUMMARY

The problem involves calculating the height a car reaches on an icy hill after skidding to a stop. The car's initial speed is 40.0 km/h (11.1 m/s), the hill's angle of inclination is 10.5 degrees, and the coefficient of kinetic friction is 0.153. The acceleration due to gravity and friction is calculated as -0.31 m/s². The correct approach to find the height involves using the kinematic equation vf² = vi² + 2a * d, where the forces acting against the car's motion include both gravity and friction.

PREREQUISITES
  • Understanding of kinematics and dynamics in physics
  • Familiarity with the concepts of friction and gravitational forces
  • Knowledge of trigonometric functions related to angles
  • Ability to manipulate and solve equations involving acceleration
NEXT STEPS
  • Review the kinematic equations for motion under constant acceleration
  • Study the effects of friction on inclined planes
  • Learn about the derivation of forces acting on an object on an incline
  • Examine similar physics problems involving energy conservation and friction
USEFUL FOR

Students studying physics, particularly those focusing on mechanics, as well as educators seeking to enhance their understanding of motion on inclined surfaces with friction.

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Homework Statement


A car with a speed of 40.0 km/h approaches the bottom of an icy hill. The hill has an angle of inclination of 10.5 degrees. The driver applies the brakes, which makes the car skid up the hill. If the coefficient of kinetic friction between the ice and the tires if 0.153, how high, measured along the incline, is the car on the hill when it comes to rest?

vi=40.0km/h=11.1m/s^2
theta=10.5 degrees
fk=0.153


Homework Equations




The Attempt at a Solution


-a=g(sinθ-ϥkcosϴ)
a=-.31m/s^2

vf^2-Vi^2/2(a)
=198.7m
 
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-a=g(sinθ-ϥkcosϴ)
shouldn't it be:
a = -g(sinθ+fkcosθ)?
both forces points in opposite direction of initial velocity. So if you choose initial velocity to be (+) direction along hill, then acceleration due friction is negative and also due gravity is negative.
 

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