You have a horizontal grindstone (a disk) that is 85 kg, has a 0.39 m radius, is turning at 85 rpm (in the positive direction), and you press a steel axe against the edge with a force of 19 n in the radial direction. 50% part (a) assuming that the kinetic coefficient of friction between steel and stone is 0.20, calculate the angular acceleration of the grindstone in rad/s2.

m = mass of disk = 85 kg

r = radius of disk = 0.39 m

moment of inertia of the disk is given as

I = (0.5) m r²

I = (0.5) (85) (0.39)² = 6.5 kgm²

F = normal applied force at the edge = 19 N

= coefficient of friction = 0.20

frictional force is hence given as

f = F

f = 0.20 x 19 = 3.8 N

= angular acceleration

Torque due to frictional force is given as

= f r

Torque is also given as

= I

hence

I = f r

inserting the values

(6.5) = (3.8) (0.39)

= 0.23 rad/s²

b.

hope this : )

a.   mass number from atomic number