High School

An electric fan is turned off, and its angular velocity decreases uniformly from 600 rev/min to 150 rev/min in 5.00 s. Find the number of revolutions made by the motor in the 5.00 s interval.

Answer :

The motor makes approximately 31.25 revolutions in 5.00 s as its angular velocity decreases uniformly from 600 to 150 rev/min.

To find the number of revolutions made by the motor in the 5.00 s interval, we first need to find the average angular velocity during this time period and then use it to calculate the number of revolutions.

Given:

Initial angular velocity, ω₁ = 600 rev/min

Final angular velocity, ω₂ = 150 rev/min

Time interval, t = 5.00 s

First, let's convert the initial and final angular velocities from rev/min to rev/s:

ω₁ = 600 rev/min = (600 rev/min) * (1 min / 60 s) = 10 rev/s

ω₂ = 150 rev/min = (150 rev/min) * (1 min / 60 s) = 2.5 rev/s

Now, we can find the average angular velocity (ω_avg) during the 5.00 s interval:

ω_avg = (ω₁ + ω₂) / 2

ω_avg = (10 rev/s + 2.5 rev/s) / 2

ω_avg = 6.25 rev/s

The number of revolutions made by the motor during the 5.00 s interval can be calculated using the formula:

Number of revolutions = ω_avg * t

Substituting the values:

Number of revolutions = 6.25 rev/s * 5.00 s = 31.25 revolutions

So, the motor makes approximately 31.25 revolutions in the 5.00 s interval.