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
Lilit [14]
3 years ago
12

A record is dropped vertically onto a freely rotating (undriven) turntable. Frictional forces act to bring the record and turnta

ble to a common angular speed. If the rotational inertia of the record is 0.54 times that of the turntable, what percentage of the initial kinetic energy is lost?
Physics
1 answer:
BartSMP [9]3 years ago
8 0

Answer:

35%

Explanation:

Assuming no external torques present during the collision between the record and the turntable, total angular momentum must be conserved.

For a rotating body with some angular velocity and moment of inertia, the angular momentum can be expressed as follows;

L = I* ω

So, as initial angular momentum and final angular momentum must be the same, we have:

Li = Lf

⇒ I₁ * ω₁ = I₂ * ω₂ (1)

where I₁ is the rotational inertia of the turntable, and I₂, is the combined rotational inertia of the turntable and the record:

I₂ = I₁ + 0.54 I₁ = 1.54 I₁

We can solve (1) for the new common angular speed, as follows:

ω₂ = ω₁ / 1.54 (2)

The initial rotational kinetic energy is given by definition for the following equation:

Kroti = 1/2 * I₁ * ω₁² (3)

The final rotational kinetic  energy takes into account the new rotational inertia and the common final angular speed:

Krotf = 1/2* I₂ * ω₂² = 1/2* 1.54 I₁* (ω₁/1.54)² (4)

Dividing both sides in (3) and (4), we get:

Krotf/Kroti = 1/1.54 = 0.65

This means that the final rotational kinetic energy, has reduced to 0.65 of the initial value, or that has lost 35% of the initial kinetic energy.

You might be interested in
To practice Problem-Solving Strategy 27.1: Magnetic Forces. A particle with mass 1.81×10−3 kgkg and a charge of 1.22×10−8 CC has
Roman55 [17]

Answer:

The magnitude of the acceleration  is a = 0.33 m/s^2

The direction is - \r k i.e the negative direction of the z-axis

Explanation:

 From  the question we are that

       The mass of the particle m = 1.8*10^{-3} kg

         The charge on the particle is q = 1.22*10^{-8}C

         The velocity is \= v = (3.0*10^4 m/s ) j

        The the magnetic field is  \= B = (1.63T)\r i + (0.980T) \r j

The charge experienced  a force which is mathematically represented as

         

                    F = q (\= v * \= B)

    Substituting value

         F = 1.22*10^{-8} (( 3*10^4 ) \r j \ \ X \ \  ( 1.63 \r i  + 0.980 \r j )T)

            = 1.22 *10^{-8} ((3*10^4 * 1.63)(\r j \ \  X \ \  \r i) + (3*10^4 * 0.980) (\r j \ \ X \ \  \r  j))

            = (-5.966*10^4 N) \r k

Note :

           i \ \ X \ \ j = k \\\\j \ \  X  \ \ k = i\\\\k  \ \ X \ \ i = j\\\\j \ \ X \ \ i = -k \\\\k \ \  X  \ \ j = -i\\\\i  \ \ X \ \ k = - j\\

Now force is also mathematically represented as

        F = ma

Making a the subject

      a = \frac{F}{m}

   Substituting values

     a =\frac{(-5.966*10^4) \r k}{1.81*10^{-3}}

        = (-0.33m/s^2)\r k

        = 0.33m/s^2 * (- \r k)

6 0
3 years ago
If you shine a light of frequency 375hz on a double slit setup , and you measure the slit separation to be 950 nm and the screen
amm1812

Answer:

y = 33.93 10⁵ m

Explanation:

This is an interference exercise, for the contributory interference is described by the expression

           d sin θ = m λ

let's use trigonometry for the angle

           tan θ = y / L

how the angles are small

          tan θ = sin θ / cos tea = sin θ

 

we substitute

         sin θ = y / L

        d y / L = m λ

         y = m λ L / d

the light fulfills the relation of the waves

       c = λ f

       λ = c / f

       λ = 3 10⁸ /375

       λ = 8 10⁵ m

first order m = 1

let's calculate

        y = 1  8 10⁵  4030 10-9 / 950 10-9

        y = 33.93 10⁵ m

6 0
3 years ago
select the example that best describes a renewable resource. a. all the houses built in the new neighborhood had natural gas ava
Bad White [126]
B. my town is powered by electricity that is generated by the energy from the flow of water through a large dam.

The water from the large dam is example of renewable energy. It can be replenished through rainfall cycle, so it is a renewable form of energy. 
4 0
3 years ago
Read 2 more answers
What is the frequency of a wave that has a period of vibration of 2 seconds?
34kurt

Answer:

The answer is 0.5 Hz

Explanation:

Its pretty easy to get the answer. One hertz (Hz) is equal to one cycle or period per second. So, just divide the period by the number of seconds.

1 period/2 secs = 1/2 Hz or 0.5 Hz

7 0
3 years ago
An electroscope is a fork-shaped device commonly used to detect the presence of charge. The tin leaves of an electroscope will s
velikii [3]

Answer:

All these is caused by the repulsion force.

Explanation:

The electroscope produces a series of electric charges that produce a repulsion force when is putted in contact with a electric charged object.

As the physics law mentions, two different forces are repealed, the electrocospe is charged negatively and the object positively, causing a repulsion force that avoids that both objects touch the other.

7 0
3 years ago
Other questions:
  • A circle in the xy-plane has diameter 9.8 cm. A magnetic field of strength 3.4 T is oriented at an angle of 23° to the z-axis, a
    15·1 answer
  • A vehicle traveling at a steady speed takes 4 hours to travel 244 km. calculate the average speed of this vehicle.
    8·1 answer
  • A girl pushes a cart with a force of 10 N. if the cart has a mass of 5 kg, what is its acceleration?
    13·1 answer
  • The temperature of the cosmic background radiation is measured to be 2.7 k. What is the wavelength of the peak in the spectral d
    14·1 answer
  • All of the following are true for slow-motion sequences EXCEPT a. slow motion ritualizes movement. b. slow motion brings gracefu
    10·2 answers
  • Describe the core-mantle-crust structures of the terrestrial worlds. What is differentiation? What do we mean by the lithosphere
    15·1 answer
  • What is one of Kepler's laws of planetary motion?
    11·1 answer
  • What is the work done by 20 Newton force applied at an angle of 45.0° to move a box a horizontal distance of 40 meters
    5·2 answers
  • A marshmallow in a vacuum becomes <br><br> A) larger. <br> B) smaller. <br> C) does not change.
    12·2 answers
  • Which type of electromagnetic radiation is useful in communications technology?
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!