Acoin is placed 35 cm from the center of a
horizontal turntable, initially at rest. the
turntable then begins to rotate. when the
speed of the coin is 110 cm/s (rotating at a
constant rate), the coin just begins to slip.
the acceleration of gravity is 980 cm/s^2
.
what is the coefficient of static friction between the coin and the turntable?

0.35

Explanation:

Sum of forces in the y direction:

∑F = ma

N − mg = 0

N = mg

Sum of the forces in the centripetal direction:

∑F = ma

Nμ = m v² / r

mgμ = m v² / r

gμ = v² / r

μ = v² / (gr)

μ = (110 cm/s)² / (980 cm/s² × 35 cm)

μ = 0.35

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.