13. Rotational Inertia & Energy

Intro to Rotational Kinetic Energy

13. Rotational Inertia & Energy

# Intro to Rotational Kinetic Energy - Video Tutorials & Practice Problems

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concept

## Intro to Rotational Kinetic Energy

Video duration:

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2

Problem

ProblemA flywheel is a rotating disc used to store energy. What is the maximum energy you can store on a flywheel built as a solid disc with mass 8 × 10^{4} kg and diameter 5.0 m, if it can spin at a max of 120 RPM?

A

4.83 × 10

^{6}JB

9.87 × 10

^{6}JC

1.97 × 10

^{7}JD

3.95 × 10

^{7}J3

example

## Mass of re-designed flywheel

Video duration:

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4

Problem

ProblemWhen solid sphere 4 m in diameter spins around its central axis at 120 RPM, it has 10,000 J in kinetic energy. Calculate the sphere's mass.

A

79 kg

B

317 kg

C

493 kg

D

1.97×10

^{6}kg## Do you want more practice?

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PRACTICE PROBLEMS AND ACTIVITIES (17)

- A wheel is turning about an axis through its center with constant angular acceleration. Starting from rest, at...
- An airplane propeller is 2.08 m in length (from tip to tip) with mass 117 kg and is rotating at 2400 rpm (rev/...
- If we multiply all the design dimensions of an object by a scaling factor f, its volume and mass will be multi...
- A uniform sphere with mass 28.0 kg and radius 0.380 m is rotating at constant angular velocity about a station...
- The flywheel of a gasoline engine is required to give up 500 J of kinetic energy while its angular velocity de...
- A 140-g baseball, with a diameter of 7.5 cm, is pitched at 145 km/h. It spins at 1200 rpm. If the baseball is ...
- An 8.0-cm-diameter, 400 g solid sphere is released from rest at the top of a 2.1-m-long, 25 incline. It rolls,...
- A thin, 100 g disk with a diameter of 8.0 cm rotates about an axis through its center with 0.15 J of kinetic e...
- What is the rotational kinetic energy of the earth? Assume the earth is a uniform sphere. Data for the earth c...
- A small 300 g ball and a small 600 g ball are connected by a 40-cm-long, 200 g rigid rod. b. What is the rotat...
- Flywheels are large, massive wheels used to store energy. They can be spun up slowly, then the wheel's energy ...
- (II) A merry-go-round has a mass of 1240 kg and a radius of 7.50 m. How much net work is required to accelerat...
- (II) Two ice skaters, both of mass 68 kg, approach on parallel paths 1.6 m apart. Both are moving at 3.5 m/s w...
- (II) Hurricanes can involve winds in excess of 120km/h at the outer edge. Make a rough estimate of(a) the ener...
- (II) Estimate the kinetic energy of the Earth with respect to the Sun as the sum of two terms, (a) that due to...
- (II) Estimate the kinetic energy of the Earth with respect to the Sun as the sum of two terms, (b) that due to...
- (III) The 1100-kg mass of a car includes four tires, each of mass 35 kg (including wheels) and diameter 0.80 m...