Question

A flywheel (I=100.0kg-m²) rotating at 500.0 rev/min is brought to rest by friction in 2.0 min. What is the frictional torque on the flywheel?

a) 2.5 N·m
b) 3.0 N·m
c) 3.5 N·m
d) 4.0 N·m

Answer 1

To find the frictional torque on the flywheel, we can use the formula T = I * α. First, calculate the angular acceleration using the formula α = (final angular velocity - initial angular velocity) / time. Then, substitute the values into the torque formula T = I * α to find the frictional torque. Using the given values, the frictional torque on the flywheel is 0 N·m.

Step-by-step explanation:

To find the frictional torque on the flywheel, we can use the formula:

T = I * α

where T is the torque, I is the moment of inertia, and α is the angular acceleration.

First, let's find the angular acceleration using the formula:

α = (final angular velocity - initial angular velocity) / time

Since the flywheel is brought to rest, the final angular velocity is 0. The initial angular velocity can be calculated by converting the given angular velocity from rev/min to rad/s:

ω = 2π * (angular velocity in rev/min) / 60

Once we have the angular acceleration, we can use the formula to find the frictional torque:

T = I * α

Substituting the values gives us:

T = (100.0 kg-m²) * α

So, the frictional torque on the flywheel is (100.0 kg-m²) * α.

To find the angular acceleration, we use the formula:

T = I * α

rearranging the formula to solve for α gives us:

α = T / I

Substituting the given values gives us:

α = (100.0 kg-m²) * (0 rad/s) / (2.0 min * 60 s/min)

Calculating the result gives us:

α = 0 rad/s²

Now we can substitute the value of α into the torque formula to find the frictional torque:

T = (100.0 kg-m²) * (0 rad/s²)

Calculating the result gives us:

T = 0 N·m

Therefore, the frictional torque on the flywheel is 0 N·m.