# Uniform Circular Motion and Forces - ClassNet

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```					Date:                    Unit #1 Forces and Motion: Dynamics                                     Page     1
Forces and Uniform Circular Motion
PART A: GOALS FOR THE LESSON

Before I leave the classroom today I should be able to …
Understand how the centripetal force is created and how it follows Newton’s Laws of Motion
Solve force problems relating to uniform circular motion in horizontal and vertical planes.
Describe some technologies that apply uniform circular motion and how they are used in
society.

PART B: CONCEPTS, DEFINITIONS, PRINCIPLES

    RECALL: UNIFORM CIRCULAR MOTION
o Objects going in a circle have a centripetal acceleration that is directed at the centre of
the circular path and an instantaneous velocity that is a tangent to the circle.

    The equations used for centripetal acceleration are

    The Centripetal Force
o

PART C: Examples

1. In a 1901 circus performance, Allo “Dare Devil” Diavolo introduced the stunt of riding a bicycle
in a loop-the-loop. Assuming that the loop is a circle with a radius 2.7 m, what is the least
speed Diavolo could have at the top of the loop if he was to remain in contact with it there?

2. A car (1600 kg) travelling at a constant speed 72 km/h along a flat curve with a radius of 190
m. What is the minimum value for the coefficient of static friction between the tires and the
road that will prevent the car from slipping?

3. You cannot always count on friction to get your car around a curve, especially if the road is icy
or wet. That is why highway curves are banked. Suppose the curve in the above question was
banked. What angle would the curve need to be banked to make reliance on friction
unnecessary?

```
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