Question

A phonograph record has an initial angular
speed of 34 rev/min. The record slows to 12
rev/min in 1.1 s.
What is the record’s average angular accel-
eration during this time interval?
Answer in units of rad/s2

Answer 1

\(\bf \textit{the phonograph went from }\cfrac{34rev}{min}\textit{ to }\cfrac{12rev}{min}\textit{ what's the difference?}\\ \quad \\
\cfrac{22rev}{min}\quad \textit{let us convert to radians over seconds first}\\ \quad \\
\cfrac{22rev}{min}\cdot \cfrac{min}{60sec}\cdot \cfrac{2\pi}{rev}\implies \cfrac{44\pi}{60sec}\)


the average acceleration will be rate of change, over how long it took

so, it only took 1.1 second for that change. so \(\bf \cfrac{\frac{44\pi}{60sec}}{1.1sec}\)