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WPCareyDevil

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**[SOLVED] (101)Horizontal/Vertical forces on an object by a turntable**

I am taking PHY 101, which I am having a little trouble with. I took a physics course in high school which I really enjoyed; a lot of what I am doing is familiar, but the specifics confuse me occasionally. I know I have solved problem A correctly, but I am confused about B

## Homework Statement

Joey puts a salt shaker near the edge and tries to spin the tray at a speed so that the shaker just barely goes around without slipping off. Joey finds that the shaker just barely stays on when the turntable is making one complete turn every two seconds. Joey's older sister measures the mass of the shaker to be 62 grams. She also measures the radius of the turntable to be 0.21 m, and she is able to calculate that the speed of the shaker as it successfully goes around in a circle is 0.6594 m/s.

(a)What is the magnitude of the horizontal part of the contact force on the shaker by the turntable?

(b) What is the magnitude of the vertical part of the contact force on the shaker by the turntable?

## Homework Equations

a)

f=ma

a=[tex]\frac{(speed)^2}{r}[/tex]

b)

?

## The Attempt at a Solution

a)

a=((.6594)^2)/.21

a=.2071 m/s^2

m=.062kg

F= .128N

b)

At first I was thinking the net force would be zero, because it is just sitting on the turntable. But, it is rotating obviously, so that isn't the case.

I drew a force diagram (back view) of the shaker sitting on the edge of the turntable with the two forces acting on it being the force of gravity on the shaker by the Earth (down) and the force on the shaker by the turntable diagonal up/left (the resultant of the frictional force[inward] (Fst) and perpendicular force[upward] (Fst)). However, I don't know how to calculate that diagonal force, which is what I am assuming to be the magnitude of net force.Thank you to all who help!