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3 years ago

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A spinning top initially spins at 16rad/s but slows down to 12rad/s in 18s, due to friction. If the rotational inertia of the to

p is 0.0004kg.m2, by how much the angular momentum of the top changes?

1 answer:

Alex Ar [27]3 years ago

5 0

Answer:

The change in angular momentum is $\Delta L = 0.0016 \ kgm^2/s$

Explanation:

From the question we are told that

The initial angular velocity of the spinning top is $w_1 = 16 \ rad/s$

The angular velocity after it slow down is $w_2 = 12 \ rad/s$

The time for it to slow down is $t = 18 \ s$

The rotational inertia due to friction is $I = 0.0004 \ kg \cdot m^2$

Generally the change in the angular momentum is mathematically represented as

$\Delta L = I *(w_1 -w_2)$

substituting values

$\Delta L = 0.0004 *(16 -12)$

$\Delta L = 0.0016 \ kgm^2/s$

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Answer:

I = 24 A

Explanation:

This is Parallel Circuit and it is the first principle of parallel circuit that voltage will be equal in all components in the circuit

It includes 10 resistors Therefore the voltage across,

R1 = R2 = R3 = R4 = R5 = R6 = R7 = R8 = R9 = R10 = voltage in battery

<h2>Ohm's Law</h2>

We will apply Ohm's Law to each resistor to find its current because we know the voltage across each resistor is 12 V and the resistance of each resistor is 5Ω

I (R1) = E (R1) / R1

I (R1) = 12v / 5Ω

I (R1) = 2.4 A

The value resistance E of all resistors are same therefore by applying the formula above the value of current in all resistors will be 2.4 A

The Total current in the circuit will be

I (total) = I (1) + I (2) + I (3) + I (4) + I (5) + I (6) + I (7) + I (8) + I (9) + I (10)

I (total) = 2.4 + 2.4 + 2.4 + 2.4 + 2.4 + 2.4 + 2.4 + 2.4 + 2.4 + 2.4

I (total) = 24 A

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3 years ago

The escape velocity of any object from Earth is 11.2 km/s. (a) Express this speed in m/s and km/h. (b) At what temperature would

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Answer:

a ) 11.1 *10^3 m/s = 39.96 Km/h

b) T_{o2} =1.58*10^5 K

Explanation:

a) $v_{es} =v_{rms}$ = 11.1 km/s =11.1 *10^3 m/s = 39.96 Km/h

b)

M_O2 = 32.00 g/mol =32.0*10^{-3} kg/mol

gas constant R = 8.31 j/mol.K

$v_{rms} = \sqrt{ \frac{3RT}{M}}$

So, $v_{rms,o2} =\sqrt{ \frac{3RT_{o2}}{M_{o2}}}$

multiply each side by M_{o2}, so we have

$v_{rms,o2}^2 *M_{o2} =3RT_{o2}$

solving for temperature T_{o2}

$T_{o2} = \frac{v_{rms,o2}^2 *M_{o2}}{3R}$

In the question given, $v_{rms} =v_{es}$

$T_{o2} = \frac{(11.1*10^3)^2 *32.0*10^{-3}}{3*8.31}$

T_{o2} =1.58*10^5 K

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Explanation:

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3 years ago

Read 2 more answers

Imagine that you have obtained spectra for several galaxies and have measured the observed wavelength of a hydrogen emission lin

Anna71 [15]

Answer:

Galaxy 1:

z = 0.0056

Galaxy 2:

z = 0.014

Galaxy 3:

z = 0.040

Explanation:

Spectral lines will be shifted to the blue part of the spectrum¹ if the source of the observed light is moving toward the observer, or to the red part of the spectrum when is moving away from the observer (that is known as the Doppler effect). The source in this particular case is represented for each of the galaxies of interest.

Hence, the redshift represents this shift of the spectral lines to red part in the spectrum of a galaxy or any object which is moving away. That is a direct confirmation of how the universe is in an expanding accelerated motion.

The redshift can be defined in analytic way by means of the Doppler velocity:

$v = c\frac{\Delta \lambda}{\lambda_{0}}$ (1)

Where $\Delta \lambda$ is the wavelength shift, $\lambda_{0}$ is the wavelength at rest, v is the velocity of the source and c is the speed of light.

$v = c(\frac{\lambda_{measured}-\lambda_{0}}{\lambda_{0}})$

$\frac{v}{c} = \frac{\lambda_{measured}-\lambda_{0}}{\lambda_{0}}$

$z = \frac{\lambda_{measured}-\lambda_{0}}{\lambda_{0}}$ (2)

Where z is the redshift.

<em>For the case of Galaxy 1: </em>

Where $\lambda_{measured} = 660.0 nm$ and $\lambda_{0} = 656.3 nm$ .

$z = \frac{\lambda_{measured}-\lambda_{0}}{\lambda_{0}}$

$z = (\frac{660.0 nm - 656.3 nm}{656.3 nm})$

$z = 0.0056$

<em>For the case of Galaxy 2: </em>

Where $\lambda_{measured} = 665.8 nm$ and $\lambda_{0} = 656.3 nm$ .

$z = \frac{665.8 nm - 656.3 nm}{656.3 nm}$

$z = 0.014$

<em>For the case of Galaxy 3:</em>

Where $\lambda_{measured} = 682.7 nm$ and $\lambda_{0} = 656.3 nm$ .

$z = \frac{682.7 nm - 656.3 nm}{656.3 nm}$

$z = 0.040$

Key terms:

¹Spectrum: Decomposition of light in its characteristic colors (wavelengths).

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3 years ago

Which of the statements below describes how a motor operates? A motor works by changing the magnetic flux to change the voltage

tigry1 [53]

Operation of a motor:

A motor takes electrical energy as input which energizes the windings of the motor and a changing magnetic field is generated which in turn generates force in the form of torque.

Let us have a look at the given options:

Option 1:

A motor works by changing the magnetic flux to change the voltage of a circuit.

This is incorrect.

Option 2:

A motor works by electrical energy moving a charge through a loop in a magnetic field, causing the loop to rotate.

This is the correct statement, this is how a motor operates.

Option 3:

A motor works by rotating a magnet in order to generate electricity.

This is incorrect since a motor consumes electricity (it does not generate electricity)

Option 4:

A motor works by using physical work to push a charge through a loop, generating a uniform magnetic field.

This is incorrect since a motor does not physical work to operate.

Therefore, the only correct statement is option 2

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