A flywheel in the form of a uniformly thick disk


Asked by wiki @ in Physics viewed by 127 People


A flywheel in the form of a uniformly thick disk of radius 1.83 m, has a mass of 24.1 kg and spins counterclockwise at 217 rpm. calculate the constant torque required to stop it in 2.25 min.

Answered by wiki @



We need to calculate the angular acceleration of the disk first.
The disk starts at 217 rpm and stops, so its final angular speed is zero, therefore the variation of angular speed is
\Delta \omega = 0 - 217 rpm =-217 rpm = -22.7 rad/s
The time interval in which the disk stops is
\Delta t=2.25 min=135 s
Therefore, the angular acceleration is
\alpha = \frac{\Delta \omega}{\Delta t}= \frac{-22.7 rad/s}{135 s}=-0.17 rad/s^2

Now, we can find the torque needed to stop the disk by using the equivalent of Netwon's second law for the rotational motions:
\tau = I \alpha
where \tau is the torque, I is the moment of inertia of the object and \alpha is the angular acceleration.
The moment of inertia for a disk is I= \frac{1}{2} mr^2 , therefore substituting this into the formula and by using the data of the exercise, we can find the torque:
\tau = ( \frac{1}{2} mr^2)\alpha = \frac{1}{2}(24.1 kg)(1.83m)^2 (-0.17rad/s^2)=-6.79kgm^2s^{-2}
where the negative sign means the torque is directed against the direction of the rotation, so anti-clockwise.

Do you know the better answer?

Similar Questions

Mr chan made 252 cookies for the annual fifth grade

Asked by wiki @ in Mathematics viewed by 44 persons

mr.chan made 252 cookies for the annual fifth grade class bake sale . they sold 3/4 of them and 3/9 of the remaining cookies were given to P.T.A members . …

What is the minimum hot holding temperature for hot dogs

Asked by wiki @ in Health viewed by 708 persons

(11) What is the minimum hot-holding temperature requirement for hot dogs? A. 125*F B. 135*F C. 145*F D. 155*F

The 400 kg mine car is hoisted up the incline

Asked by wiki @ in Physics viewed by 183 persons

The 400 kg mine car is hoisted up the incline using the cable and motor M. For a short time, the force in the cable is F= (3200) N, where …

The formation of the hawaiian islands is one example of

Asked by wiki @ in Biology viewed by 207 persons

The formation of the Hawaiian Islands is one example of a. volcanoes forming over a hot spot. b. volcanoes forming along plate boundaries. c. the Ring of Fire. d. random …

Which number line represents the solutions to x 4 2

Asked by wiki @ in Mathematics viewed by 240 persons

Which number line represents the solutions to |x + 4| = 2?

Compare macroeconomics and microeconomics and give an example of each

Asked by wiki @ in Mathematics viewed by 206 persons

What is the difference between microeconomics and macroeconomics? a. Macroeconomics deals with abstract economic theories, while microeconomics applies those theories to the real world. b. Microeconomics looks at economic systems …

What foreign dictator did this american think had good ideas

Asked by wiki @ in History viewed by 287 persons

What foreign dictator did this American think had good ideas? A. Will Rogers - Adolf Hitler B. Charles Lindbergh - Joseph Stalin C. Philip LaFollette - Benito Mussolini

How many grams are in 4.5 moles of lithium oxide

Asked by wiki @ in Chemistry viewed by 213 persons

How many grams are in 4.5 moles of lithium oxide?

What was the economy like in the new england colonies

Asked by wiki @ in History viewed by 164 persons

New england colonies and their economy

Kuta software solving systems of equations by substitution with work

Asked by wiki @ in Mathematics viewed by 264 persons

Kuta Software - Infinite Pre-Algebra NameSolving Systems of Equations by SubstitutionDateSolve each system by substitution.1) y = 7x-10y=-32) y=-8y=-2x - 123) y=6x …

Y 2x 9

Asked by wiki @ in Mathematics viewed by 163 persons

Solve y= -2x + 9 y= 4x -3

What nutrients makes up the greatest percentage of the body

Asked by wiki @ in Biology viewed by 137 persons

What nutrient makes up the greatest percentage of the body?

David scott drops a hammer and feather on the moon

Asked by wiki @ in Physics viewed by 84 persons

Apollo astronaut David Scott dropped a hammer and a feather together on the Moon, and both reached the ground at the same time. What are the two distinct advantages that …

What phase of the cell cycle does the cell grow

Asked by wiki @ in Mathematics viewed by 155 persons

During what phase of the cell cycle does cell division occur? During what phase of the cell is DNA replicated? During what phase of the cell cycle does the cell …

How does food with proper nutrients benefit you points 1

Asked by wiki @ in Health viewed by 184 persons

HEALTH QUESTIONS this is lesson quiz 3.03 from k12. Please only answer of you know two or more answers. :) Eating whole foods when young reduces the risk of developing …

Why are free market economies able to attain economic growth

Asked by wiki @ in History viewed by 203 persons

Why are free market economies able to attain economic growth? A. Consumers can purchase all the goods they need, which causes firms to produce more. B. Competition encourages innovation, which …

When did the first aids treatment program start in africa

Asked by wiki @ in Health viewed by 183 persons

When did the first AIDS treatment program start in Africa? a. 1996 b. 1999 c. 2001 d. 2002

What is the lcd of 1 3 and 3 7

Asked by wiki @ in Mathematics viewed by 72 persons

What is the LCD of 1/3 and 3/7?

Ask not what your country can do for you essay

Asked by wiki @ in English viewed by 285 persons

And so, my fellow Americans: ask not what your country can do for you - ask what you can do for your country, Martice read Kennedy's speech in English class …

Solve x 2 2x 4 0 by completing the square

Asked by wiki @ in Mathematics viewed by 245 persons

Solve x2 + 2x = 4 for x by completing the square. x equals plus or minus square root of 5 plus 1 x equals plus or minus square root …

A 15.0 kg block is attached to a very light

Asked by wiki @ in Physics viewed by 168 persons

A 15 kg block is attached to a very light horizontal spring of spring constant 500 N/m and is resting on a frictionless horizontal table as shown in the figure. …

The amount of energy or fuel in food is called

Asked by wiki @ in Health viewed by 331 persons

The amount of energy or fuel in food is called ____________.

How many ounces of oil for 40 to 1 ratio

Asked by wiki @ in Mathematics viewed by 188 persons

A leaf blower runs on a mixture of gas and oil. The ratio of ounces of gas to ounces of oil is 40 to 1. How many ounces of gas …

How do trade agreements of international organizations affect trade

Asked by wiki @ in English viewed by 198 persons

How do trade agreements of international organizations affect trade? by encouraging the development of trade policies by eliminating tariffs and taxes on imports and exports by encouraging countries to balance …

What molecule is a common energy source for living organisms

Asked by wiki @ in Geography viewed by 169 persons

This type of molecule is the MOST common energy source for all cells and enters the cell by facilitated diffusion. The molecule is

El concierto de jazz a las ocho de la noche

Asked by wiki @ in Spanish viewed by 299 persons

1. El concierto de jazz a las ocho de la noche. 2. Inés y Pancho preocupados porque el examen va a ser difícil. 3. La playa sucia porque hay muchos …

Character who experiences conflict in the story drives the action

Asked by wiki @ in English viewed by 196 persons

Character who experiences conflict in the story; drives the action Flat Character Antagonist Protagonist Static Character

Is the act of working in exchange for an income

Asked by wiki @ in Business viewed by 162 persons

What is the act of working in exchange for an income.?

In how many cities are federal reserve district banks located

Asked by wiki @ in Business viewed by 206 persons

In how many cities are Federal Reserve district banks located? 4 12 50 8

How many quarts in a 1 2 bushel of peaches

Asked by wiki @ in Mathematics viewed by 248 persons

The volume of dry goods, like apples or peaches, can be measured usings bushels, pecks, and quarts. A bushel contains 4 pecks, and a peck contains 8 quarts. What is …

Most viewed questions in Physics


A 0.25 kg arrow with a velocity of 12m s

Asked by wiki @ in Physics viewed by 855 persons


Uranium 235 undergoes an alpha decay to produce thorium 231

Asked by wiki @ in Physics viewed by 840 persons


Water waves in a small tank are 06 m long

Asked by wiki @ in Physics viewed by 745 persons



A golf club hits a stationary 0.050 kilogram golf ball

Asked by wiki @ in Physics viewed by 740 persons


In which electric circuit would the voltmeter read 10 volts

Asked by wiki @ in Physics viewed by 681 persons


A tank of water in the shape of a cone

Asked by wiki @ in Physics viewed by 681 persons



A 90 kg person rides a spinning amusement park ride

Asked by wiki @ in Physics viewed by 670 persons


The initial speed of a cannonball is 0.20 km s

Asked by wiki @ in Physics viewed by 660 persons


How many times does your heart beat during your lifetime

Asked by wiki @ in Physics viewed by 658 persons



All of the following are advantages of outsourcing except it

Asked by wiki @ in Physics viewed by 631 persons


A 60 kilogram student jumps down from a laboratory counter

Asked by wiki @ in Physics viewed by 629 persons


A 5.8 x 10 4 watt elevator motor can lift

Asked by wiki @ in Physics viewed by 613 persons



A golfer hits a ball at an angle of 25

Asked by wiki @ in Physics viewed by 586 persons


7 types of electromagnetic waves from lowest to highest frequency

Asked by wiki @ in Physics viewed by 556 persons


Which of the following statements about diffusion is true

Asked by wiki @ in Physics viewed by 527 persons