1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
KatRina [158]
3 years ago
12

Calculate the angular momentum, in kg · m2/s, of an ice skater spinning at 6.00 rev/s given his moment of inertia is 0.310 kg ·

m2. kg · m2/s (b) He reduces his rate of spin (his angular velocity) by extending his arms and increasing his moment of inertia. Find the value of his moment of inertia, in kg · m2, if his angular velocity drops to 2.45 rev/s. kg · m2 (c) Suppose instead he keeps his arms in and allows friction with the ice to slow him to 3.00 rev/s. What average torque, in N m, was exerted if this takes 18.0 seconds? (Indicate the direction with the sign of your answer. Assume that the skater's rotation is in the positive direction.) N · m
Physics
2 answers:
steposvetlana [31]3 years ago
8 0

Answer:

a) 11.7 kg. m2/s b) 0.76 Kg. m2 c) -0.33 N.m

Explanation:

a)

  • Assuming no external torques act on the skater, total angular momentum must be conserved:

        L1 = L2

        As the angular momentum can be calculated as the

        product of the moment of inertia times the angular velocity,

we can write:

       I1*ω1 = I2*ω2  

       The initial angular momentum can be written as follows:

       I1*ω1= 0.31 kg.m2 * 6.0 rev/sec  

       As we need to express the angular momentum in kg.m2/s, we need to convert the angular velocity units, from rev/sec to rad/sec, as follows:

       ω1= 6.0 rev/sec (2π rad/ rev) = 12 π rad/sec

       I1*ω1= 0.31 kg.m2 * 12 π rad/sec = 11.7 kg. m2/s

b)

  • As the final angular momentum must be the same, and we know the value of the final angular velocity, we can replace by the values in L2, and solve for I2, as follows:

        I2 = I1*( ω1 / ω2) = 0.31 kg. m2 . 6.0/2.45 = 0.76 kg.m2

c)

  • If an external torque is present, we can write the following equation, that relates the external torque with the rotational inertia and the angular acceleration, as follows:

        Τ= I *γ (1)

        Where γ, is the angular acceleration.

        By definition, γ is the rate of change of the angular velocity,

        so if we have the values of  the initial and final angular

        velocities, and the time passed, we can express γ as

follows:

       γ= (ω2 – ω1) / t

       In order to express γ in rad/sec2, we need to convert the

angular  velocities (given in rev/sec), to rad/sec, as follows:

       ω1= 6.0 rev/sec (2π rad/ rev) = 12 π rad/sec

       ω2= 3.0 rev/sec (2π rad/ rev) = 6 π rad/sec

       Solving for γ:

       γ = -6 π / 18. 0 rad/sec2 = -1.05 rad/sec2

       Replacing in (1), we have:

       τ= 0.31 kg. m2.*(-1.05 rad/sec2) = -0.33 N.m

Brrunno [24]3 years ago
3 0

Answer:

a) The angular momentum is 11.69 kg m²/s

b) The moment of inertia is 0.76 kg m²

c) The torque is -0.3255 N

Explanation:

please look at the solution in the attached Word file

Download docx
You might be interested in
If you blow across the open end of a soda bottle and produce a tone of 250 Hz, what will be the frequency of the next harmonic h
Naddika [18.5K]

Answer:

Generally, the lowest overtone for a pipe open at one end and closed would be at  y / 4  where y represents lambda, the wavelength.

Since F (frequency) = c / y       Speed/wavelength

F2 / F1 = y1 / y2      because c is the same in both cases

F2 = y1/y2 * F1

F2 = 3 F1 = 750 /sec

Note that L = y1 / 4 = 3 y2 / 4 for these wavelengths to fit in the pipe

and y1 = 3 y2

8 0
2 years ago
You throw a glove straight upward to celebrate a victory. Its initial kinetic energy is K and it reaches a maximum height h. Wha
Rasek [7]

Answer:

K/2

Explanation:

The law of conservation of mechanical energy states that the sum of the kinetic and potential energies is a constant at any point.

At maximum height, the glove has purely potential energy but at the bottom, it has purely kinetic energy.

The potential energy at the top = kinetic energy at the bottom. The potential energy is given by

PE = mgh

At half height, this potential energy is

PE = \frac{1}{2}mgh

At this height, PE + KE = Constant = KE at bottom or PE at maximum height.

mgh = \frac{1}{2}mgh +KE

KE = \frac{1}{2}mgh = K/2

5 0
3 years ago
Is the refraction different entering medium that has a higher index of refraction compared to entering amedium that has a lower
oee [108]

Answer:

Yes

Explanation:

The speed of light when it travels through glass, diamond, etc, the light travels at different speed from the speed of light. Speed of the light in material is related to the index of refraction.

The change in speed which occurs when the light passes from one medium to the another is responsible for bending of the light which is called as refraction.

<u>When the light goes into a medium with the higher index of the refraction, light bends towards normal. Conversely, if the light traveling goes from higher refractive index to lower refractive index, it will bend away from the normal. </u>

<u>Hence, the refraction is different in both the scenario.</u>

6 0
3 years ago
Over 4 seconds, a car's momentum decreases by 1000 kg m/s how much force did it take to make this happen?
kotykmax [81]

Answer:

250N

Explanation:

Given parameters:

Time  = 4s

Momentum  = 1000kgm/s

Unknown:

Force  = ?

Solution:

To solve this problem, we use Newton's second law of motion;

      Ft  = Momentum

F is the force

t is the time

So;

          F x 4 = 1000kgm/s

          F  = 250N

6 0
3 years ago
Which statement about the image Formed by a plane mirror is correct?
lbvjy [14]

Answer:

The image is virtual

number-4

8 0
3 years ago
Other questions:
  • Suppose you are driving in a car. A truck drives past you, traveling in the same direction you are driving. Which statement best
    5·1 answer
  • Which speed is at the sound barrier?
    5·2 answers
  • A circuit consists of a series combination of 5.50 âkΩ and 5.00 âkΩ resistors connected across a 50.0-V battery having negligi
    7·1 answer
  • An object of mass 0.50 kg is transported to the surface of Planet X where the object's weight is measured to be 20 N. The radius
    14·1 answer
  • A meter stick balances horizontally on a knife-edge at the 50.0 cm mark. With two 5.12 g coins stacked over the 24.2 cm mark, th
    5·1 answer
  • Part A: A group of students performed the same "Ohm's Law" experiment that you did in class. They obtained the following results
    13·1 answer
  • What variable(s) determine the amount of potential energy an object has?
    13·1 answer
  • Please help me i need it it’s the only way i’ll pass
    7·1 answer
  • Which has the greater acceleration, a person going from 0 m/s to 10 m/s in 10 seconds or an ant going from 0 m/s to 0.25 m/s in
    12·1 answer
  • Which two changes would decrease the electric force between two charged
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!