Question

"Маховик, имеющий форму диска массой 30 кг и радиусом 10 см, был раскручен до частоты 300 мин-1. Под действием силы трения диск остановился через 20 с. Найти момент сил трения, считая его постоянным.,и" в категории "Физика".

Answer 1

M=-J*w/dt w=2*pi*n   J=m*R^2/2
M=-m*R^2*4*pi^2*n2/2*dt=30*0,01*4*9,86*25/2*20=-7,4 Н*м

Answer 2

Calculation of Frictional Force

To find the moment of frictional force acting on the disk, we need to use the formula:

Frictional Force (F) = Moment of Inertia (I) * Angular Acceleration (α)

The moment of inertia of a disk is given by the formula:

Moment of Inertia (I) = (1/2) * Mass (m) * Radius^2

Given: - Mass of the disk (m) = 30 kg - Radius of the disk (r) = 10 cm = 0.1 m - Initial angular velocity (ω) = 300 min^(-1) = 300 * 2π rad/s - Time taken to stop (t) = 20 s

First, let's calculate the moment of inertia (I):

I = (1/2) * m * r^2

Substituting the given values:

I = (1/2) * 30 kg * (0.1 m)^2

Now, let's calculate the angular acceleration (α):

α = (Final Angular Velocity - Initial Angular Velocity) / Time

Since the disk stops rotating, the final angular velocity is 0 rad/s.

α = (0 - 300 * 2π rad/s) / 20 s

Now, we can calculate the frictional force (F):

F = I * α

Substituting the values of I and α:

F = [(1/2) * 30 kg * (0.1 m)^2] * [(0 - 300 * 2π rad/s) / 20 s]

Calculating the above expression will give us the value of the frictional force.