- #1
PhyIsOhSoHard
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Homework Statement
A car is resting on a curved path in point A as seen in the picture. The mass of the car is known.
The angle θ and the radius of the curved path are known.
The kinetic coefficient of friction is known.
The car starts gliding backwards on the curved path. What is the acceleration of the car when it starts gliding from point A?
State both the magnitude and the direction of the acceleration.
The Attempt at a Solution
I start by drawing the free body diagram. Since the acceleration of a circular motion is directed towards the center, then I already know the direction of the acceleration. I also draw the normal force (n) the gravity force (mg) and the kinetic friction force (fk):
I rotate the coordinatesystem with θ degrees:
I now use Newton's second law on the horizontal forces only (since there is no acceleration vertically).
[itex]\uparrow \sum F_y=ma_{rad}[/itex]
[itex]n-mg \cdot cos(\theta)=ma_{rad}[/itex]
[itex]a_{rad}=\frac{n}{m} \cdot g \cdot cos(\theta)[/itex]
But I don't know the normal force? :(