PHYSICS HIGH SCHOOL

An ice skater has a moment of inertia of 5.0 kgm2 when her arms are outstretched. at this time she is spinning at 3.0 revolutions per second (rps). if she pulls in her arms and decreases her moment of inertia to 2.0 kgm2, how fast will she be spinning?

Answers

Answer 1
Answer: With arms outstretched,
Moment of inertia is I = 5.0 kg-m².
Rotational speed is ω = (3 rev/s)*(2π rad/rev) = 6π rad/s
The torque required is
T = Iω = (5.0 kg-m²)*(6π rad/s) = 30π 

Assume that the same torque drives the rotational motion at a moment of inertia of 2.0 kg-m².
If u = new rotational speed (rad/s), then
T = 2u = 30π
u = 15π rad/s
   = (15π rad/s)*(1 rev/2π rad)
   = 7.5 rev/s

Answer: 7.5  revolutions per second.


Related Questions

HIGH SCHOOL

One of the games at a carnival involves trying to ring a bell with a ball by hitting a lever that propels the ball into the air. The height of the ball is modeled by the equation h(t)= -16t^2+39t. if the bell is 25ft above the ground, will it be hit by the ball?

Answers

Answer:

Ball will not hit bell.

Explanation:

The height of the ball is modeled by the equation h(t)= -16t²+39t

We need to find if the bell is 25 ft above the ground, will it be hit by the ball.

So we need to find maximum height of the ball.

For maximum height we have

                   

Substituting in h(t) = -16t²+39t

Maximum height reached = h(1.22) = -16 x 1.22²+39 x 1.22 = 23.77 ft

So maximum height reached is less than height of bell.

Ball will not hit bell.

HIGH SCHOOL

A bike rider pedals with constant acceleration to reach a velocity of 7.5 (vf)m/s over a time of 4.5 s(t). during the period of acceleration, the bike's displacement is 19 m(d). what was the initial velocity of the bike?

Answers

The initial velocity of the bike was 1.67 (vf)m/s. This is found by evaluating 7.5/4.5 which yields the velocity per unit of time which is equivalent to initial velocity.
HIGH SCHOOL

How to generate electricity from biogas?

Answers

The same way as electricity is generated from any other gas:

-- Burn the gas.
-- Use the heat to boil water.
-- Pipe the steam through the fan of a turbine.
-- Use the rotation of the turbine to spin an electric-power generator.
COLLEGE

A magnetic field is uniform over a flat, horizontal circular region with a radius of 2.00 mm, and the field varies with time. Initially the field is zero and then changes to 1.50 T, pointing upward when viewed from above, perpendicular to the circular plane, in a time of 115 ms. (a) what is the average induced emf around the border of the circular region? (Enter the magnitude in μν and the direction as seen from above.) magnitude direction Selet as seen from above
(b) Immediately after this, in the next 65.0 ms, the magnetic field changes to a magnitude of 0.500 T, pointing downward when viewed from above. What is the average induced emf around the border of the circular region over this time period? (Enter the magnitude in uv and the direction as seen from above.) magnitude direction cas seen from above.

Answers

The production of a potential difference in a coil due to magnetic flux is known as the induced emf. The average induced emf will be 0.00016391 V.

What is a magnetic field?

It is the type of field where the magnetic force is obtained. With the help of a magnetic field. The magnetic force is obtained it is the field felt around a moving electric charge.

(a) 0.00016391 V  is the average induced emf around the border of the circular region.

The given data in the problem is;

r is the  radius of horizontal circular region = 2.00 mm=0.002 m

is the initial megnetic field=0T

s the final megnetic field= 1.5 T

t  is the time taken= 115 ms0.115 sec

is the emf induced =?

The induced emf is found by;

Hence  0.00016391 V  is the average induced emf around the border of the circular region.

(b) 0.00038665 V is the average induced emf around the border of the circular region over this time period.

The given data in the problem is;

r is the  radius of horizontal circular region = 2.00 mm,

is the initial megnetic field=+1.5 T

s the final megnetic field= -1.5 T

t  is the time taken= 65 ms=0.065 sec

is the emf induced =?

Hence 0.00038665 V is the average induced emf around the border of the circular region over this time period.

To learn more about the magnetic field refer to the link;

brainly.com/question/19542022

Answer:

0.00016391 V

0.00038665 V

Explanation:

r = Radius = 2 mm

= Initial magnetic field = 0

= Final magnetic field = 1.5 T

t = Time taken = 115 ms

Induced emf is given by

The magnitude of the induced emf is 0.00016391 V

t = 65 ms

The magnitude of the induced emf is 0.00038665 V

COLLEGE

Assume that the average distance of the sun from the earth is 400 times the average distance of the moon from the earth. Now consider a total eclipse of the sun and state conclusions that can be drawn about (a) the relation between the sun's diameter and the moon's diameter; (b) the relative volumes of sun and moon. (c) Find the angle intercepted at the eye by a dime that just eclipses the full moon and is placed at a distance of 2 m from your eye. From this result and the given distance between moon and earth , estimate the diameter of the moon. Use 20 mm for diameter of dime

Answers

Answer:

a) Since the sun is 400 times a moon's distance from earth, that must mean it looks 400 times smaller than it would if it were a moon's distance away. If the moon eclipses the sun perfectly, then that means that the sun is 400 times larger than the moon. Therefore the diameter of the sun is also 400 times larger than the diameter of the moon.

b) If the sun is 400 times bigger than the moon, then the radius of the sun is also 400 times bigger than the radius of the moon. The volume of a sphere is given by 4 3 π r 3 43πr3. If the moon's radius is r, then the sun's radius is 400r. The volume of the sun will then be 6.4×107 times larger than the volume of the moon.

c) the angular size is 2 arctan 0.09 ≈ 10.286 2arctan⁡0.09≈10.286. Using similar triangles, where the height of the new triangle is the given distance to the moon from Earth, then I would calculate the diameter of the moon as 2 ⋅ ( 3.8 × 10 5 ) tan 5.14 2⋅(3.8×105)tan⁡5.14 kilometers ≈ 6.84 × 10 4 ≈6.84×104 kilometers.

HIGH SCHOOL

If the unemployment rate is rising, what part of the business cycle is the economy most likely experiencing? A. Peak B. Expansion
C. Spiral
D. Recession

Answers

Answer: D. Recession

Explanation:

A recession can be define as the part of the business cycle in which the economy declines for a period of at least six months. The decrease in the economy can be detected by drop in five economic indicators such as employment rate, manufacturing, income, gross domestic product and retail sales.

On the basis of the above explanation, recession is the part of the business cycle in which the unemployment rate rises.

D. Recession 

because the unemployment is rising which is more people loosing their jobs and recession means a decline in something
HIGH SCHOOL

Which of the following is an important step in the process of conflict resolution? A. defining the problem and proposing a solution
B. requiring all participants to adopt your viewpoint
C. agreeing only with your own values
D. none of the above
(Whoever answers it first gets brainliest!!!! Plzzzzz help!!!!)

Answers

A. The important step in the process of conflict resolution is defining the problem and proposing a solution.

What do you mean by conflict?

"Conflict is defined as a clash between individuals arising out of a difference in thought process, attitudes, understanding, interests, requirements and even sometimes perceptions."

How to resolve a conflict?

"To resolve a conflict first of all, one should find the root cause of the problem and he should work on the solution that is acceptable to all in this way the conflict can be removed."

To know more about conflict here brainly.com/question/22522689

#SPJ2

A would be the correct answer. Its the only one to make sense since you are trying to solve the conflict!
COLLEGE

A water skier notices that the distance between successive wave crest is 12 meters. The wave crests pass his boat every 4.8 seconds. How fast are the waves traveling?a.456Hzb. 638Hzc. 368Hzd. 213Hz

Answers

Answer:

The velocity of wave=2.5 m/s

Explanation:

We are given that

The distance between successive wave crest=

Time =

We have to find the the velocity of wave.

Frequency of wave=

The relation between frequency, wavelength and velocity is given by

Hence, the velocity of wave= 2.5 m/s

HIGH SCHOOL

Express 0.00000000062 kg in scientific notation. 6.2 x 1010kg 6.2 x 10-10kg 0.62 x 10-9kg

Answers

I believe the correct answer from the choices listed above is the second option. The scientific notation of the measurement 0.00000000062 kg would be 6.2 x 10^-10 kg. Scientific notation is used to express too large and too small values of numbers. Hope this helps. Have a nice day.
Answer:

The scientific form of a number is:

                       

Explanation:

We are given a number which we have to express in scientific notation.

We know that a number is expressed in scientific notation as follows:

  • There must be one digit before the decimal.
  • If the decimal is shifted to the left then the number of shift takes the positive power of 10 and if the shift is to the right then the number of shift takes negative power of 10.

Here we have a number as:

Now we have to shift the decimal 10 places to the right.

Hence, the  number in scientific form is:

     

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