# Physics 12

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I've been doing alot of extra questions for physics lately, and these four are still giving me trouble. Please help me out and help me solve them, including Free Body Diagrams if possible.

1. If a curve with a radius of 60m is properly banked for a car travelling at 60km/hr, what must the coefficient of static friction be for a car not to skid when travelling at 90km/hr?

2. A satellite of mass "m" moves in a circular orbit about the earth at a height "h" above its surface. If the radius of the earth is R and the accel due to gravity at the earth's surface is "g" show that the period of the satellite can be expressed as T=2pi*route((R+h)^3 / gR^2)

3. Calculate the mass of the sun using the fact that the period of the earth is 3.16x10^7 seconds and its mean distance from the sun is 1.5x10^11m. (G=6.67x10^-11 Nm^2/kg^2)

4. Conical pendulum question-
An amusement park ride consists of a rotating circular platform 8m in diameter from which seats are suspended at the end of 2.5m chains. When the system rotates the cahins holding the seats make an angle theta=28degrees with the vertical a) what is the speed of the seat? b) If a child of mass 40kg sits in the 10kg seat, what is the tension in the chain?

Thanks huge guys, if I can see how these questions are done, i should be set for my midterm exam.

• Physics 12 -

I strongly recommend you obtain a copy of Schaum's Outline Series for Physics, available at any college bookstore, or at Barnes Noble. Very reasonalbly priced, and a valuable asset of solve problems.

• Physics 12 -

Morning bump!