Test+Review

=**#1.Definition**s= Rotational Speed- the number of rotations per unit of time. Centripital Force- the force that causes an object to follow a circular path. Friction- a force that applies all motion sometimes causes heat. Coloumb's Law- the relationship among electrical forces, charges, and distance.
 * Kinetic Friction force Ff1 kinetic= mkFN**
 * Static Friction Force 0< Ff static < msF**

#2. **Examples**
Rotational speed- a Ferris wheel rotating at a certain amount of time. A projected space station consists of a circular tube that will rotate about its center. The circle formed by the tube has a diameter of about 1.1km. What must be the rotation speed ( rev per day) if an effect equal to gravity at the surface of the earth(1.0g) is to be felt? a = rω² → ω = √(a/r) = √(9.8/1100) = .09438 rad/sec
 * //Example//**


 * 86400sec/day*1rev/2π rad = 1297.928 rev/day

Centripetal force- the gravitational pull pulling the earth in a circular motion. //**Example**// What is the centripetal force acting on this 100kg person if he is spun around in a 8 m circle at a speed of 10 m/s? m = 100 kg, r = 8 m, v = 10 m/s __Step 1:__ Substitute the values in the below centripetal force formula: This example will guide you to calculate the Centripetal Force manually.

Friction Force- when you rub your hands together they get hot //**Example**// Kinetic Friction force Ff1 kinetic= mkFN Static Friction Force 0< Ff static < msF

Coloumb's law- two batteries making an object work //**Example**// Problem: How many coulomb's of charge is contained in the electrons of one kg of hydrogen? Solution: One kg of hydrogen is 1000 grams, and has therefore 1000 times Avagadro's number of electrons. Q = 1000* NA * e where e = 1.602E-19 (C), and NA = Avogadro's number = 6.02E23 Q = -4.82E7 (C)

#3.**Citations**

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