Skip to main content

Learning Introductory Physics with Activities

Paul J. Emigh, Rebecka Tumblin, Kathryn Hadley, Danielle Skinner

Section 11.10 Practice - Rotational Motion

Subsection Practice

Calculation 11.10.1. Crankshaft.

The crankshaft (\(r = 3 \mathrm{~cm}\)) in a race car accelerates uniformly from rest to \(3000 \mathrm{~rpm}\) in \(2.0 \mathrm{~s}\text{.}\) How many revolutions does it make?
  1. 10 revolutions
  2. 25 revolutions
  3. 42 revolutions
  4. 50 revolutions
  5. 63 revolutions
  6. 101 revolutions
Answer.
D.

Calculation 11.10.2. Angular motion.

A 60 cm diameter wheel accelerates from rest at a rate of \(7 \mathrm{~rad/s^2}\text{.}\)
  1. What is the tangential acceleration of a point on the edge of the wheel?
  2. How long does it take for the wheel to turn through 14 rotations?
  3. After the wheel has undergone 14 rotations, what is the radial component of the acceleration on the edge the wheel?
Answer 1.
\(2.1 \mathrm{~m/s^2}\)
Answer 2.
\(5.01 \mathrm{~s}\)
Answer 3.
\(739 \mathrm{~m/s^2}\)

Calculation 11.10.3. Army the Armadillo.

The Brazilian three-banded armadillo has a hard outer exterior, and when it senses danger, it rolls into a ball for protection. Suppose that Army the armadillo rolls into a ball (with a \(5 \mathrm{~cm}\) radius) while on the slope of a hill. As a result, they begin to roll down the hill; and after \(15 \mathrm{~s}\text{,}\) they have undergone \(45.8\) revolutions. What is Army’s angular speed at this time?
  1. \(\displaystyle 12.7 \mathrm{~rad/s}\)
  2. \(\displaystyle 15.5 \mathrm{~rad/s}\)
  3. \(\displaystyle 22.0 \mathrm{~rad/s}\)
  4. \(\displaystyle 29.1 \mathrm{~rad/s}\)
  5. \(\displaystyle 38.4 \mathrm{~rad/s}\)
How fast is Army traveling at this point?
  1. \(\displaystyle 1.92 \mathrm{~m/s}\)
  2. \(\displaystyle 2.23 \mathrm{~m/s}\)
  3. \(\displaystyle 3.49 \mathrm{~m/s}\)
  4. \(\displaystyle 4.24 \mathrm{~m/s}\)
  5. \(\displaystyle 5.56 \mathrm{~m/s}\)
Answer 1.
D.
Answer 2.
A.

References References

[1]
  
Practice activities provided by BoxSand: https://boxsand.physics.oregonstate.edu/welcome.
<Prev^TopNext>