122k views
4 votes
The motor A accelerates uniformly from zero to 3800 rev/min in 19 seconds after it is turned on at time t = 0. It drives a fan (not shown) which is attached to drum B. The effective pulley radii are shown in the figure. Determine (a) the number of revolutions turned by drum B during the 19-second startup period, (b) the angular velocity of drum B at time t = 8 s, and (c) the number of revolutions turned by drum B during the first 8 seconds of motion. Assume no belt slippage.

User Fxstein
by
8.4k points

1 Answer

3 votes

Final answer:

In this problem, we are given the initial angular velocity and angular acceleration of a disk and we need to find its angular velocity at a given time, the angle it has rotated through, and the tangential acceleration of a point on the disk.

Step-by-step explanation:

To solve this problem, we need to use the equations of rotational motion. Let's go step by step:

a) We can find the angular velocity of the disk at t = 5.0 s using the equation:

angular velocity (w) = initial angular velocity (w0) + angular acceleration (alpha) * time (t)

Plugging in the values, we get:

w = 2.0 rad/s + (1.0 rad/s²)(5.0 s) = 2.0 rad/s + 5.0 rad/s = 7.0 rad/s

b) To find the angle the disk has rotated through during this time, we can use the equation:

angle (theta) = initial angular velocity (w0) * time (t) + 0.5 * angular acceleration (alpha) * time (t)²

Plugging in the values, we get:

theta = (2.0 rad/s)(5.0 s) + 0.5(1.0 rad/s²)(5.0 s)² = 10.0 rad + 0.5(1.0 rad/s²)(25.0 s²) = 10.0 rad + 0.5 rad = 10.5 rad

c) To find the tangential acceleration of a point on the disk at t = 5.0 s, we can use the equation:

tangential acceleration (a) = radius of the disk (r) * angular acceleration (alpha)

Plugging in the values, we get:

a = (0.10 m)(1.0 rad/s²) = 0.10 m/s²

User Colin Anthony
by
7.6k points