A flywheel flows from 250rpm to 150rpm in 4.2 seconds. How many revolutions occur during this time
1 answer:
Answer:
7revolutions
Explanation:
Given parameters:
Initial revolution = 250rpm
Final revolution = 150rpm
Time = 4.2s
Unknown:
Number of revolutions that occur at this time = ?
Solution:
To solve this problem;
let us find the change in revolution = 250rpm - 150rpm = 100rpm
Convert the time to seconds;
60s makes 1 minute
4.2s will make = 0.07min
So;
The number of revolutions at this time = 100rpm x 0.07min
= 7revolutions
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Explanation:
(a) The given data is as follows.
Length of the rod, L = 0.83 m
Mass of the rod, m = 110 g = 0.11 (as 1 kg = 1000 g)
At the lowest point, angular speed of the rod () = 5.71 rad/s
First, we will calculate the rotational inertia of the rod about an axis passing through its fixed end is as follows.
I =
=
=
= 0.00631 + 0.415
= 0.42131
Therefore, kinetic energy of the rod at its lowest point will be calculated as follows.
K =
=
= 6.86 J
Hence, kinetic energy of the rod at its lowest point is 6.86 J.
(b) According to the conservation of total mechanical energy of the rod, we have
or, mgh = K = 6.86 J
Therefore, h =
=
= 0.584 m
Hence, the center of mass rises 0.584 m far above that position.