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3 years ago

Why quantity refractive index dooesn't have unit

2 answers:

5 0

Refractive Index is a ratio of two similar physical quantity which is dimension less
refractive index = sin I / sin r

therefore it doesn't have a unit.

LenaWriter [7]3 years ago

4 0

Refractive index is expressed as a ratio of speed of light in vacuum relative to the speed of considered medium. As it is a ratio and the units m/s or km/h cancel out each other. Therefore, the qauntity refractive index does not have any unit. I hope it will be helpful to you. Thank you

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A constant torque of 3 Nm is applied to an unloaded motor at rest at time t = 0. The motor reaches a speed of 1,393 rpm in 4 s.

irakobra [83]

Answer:

The moment of inertia of the motor is 0.0823 Newton-meter-square seconds.

Explanation:

From Newton's Laws of Motion and Principle of Motion of D'Alembert, the net torque of a system ( $\tau$ ), measured in Newton-meters, is:

$\tau = I\cdot \alpha$ (1)

Where:

$I$ - Moment of inertia, measured in Newton-meter-square seconds.

$\alpha$ - Angular acceleration, measured in radians per square second.

If motor have an uniform acceleration, then we can calculate acceleration by this formula:

$\alpha = \frac{\omega - \omega_{o}}{t}$ (2)

Where:

$\omega_{o}$ - Initial angular speed, measured in radians per second.

$\omega$ - Final angular speed, measured in radians per second.

$t$ - Time, measured in seconds.

If we know that $\tau = 3\,N\cdot m$ , $\omega_{o} = 0\,\frac{rad}{s }$ , $\omega = 145.875\,\frac{rad}{s}$ and $t = 4\,s$ , then the moment of inertia of the motor is:

$\alpha = \frac{145.875\,\frac{rad}{s}-0\,\frac{rad}{s}}{4\,s}$

$\alpha = 36.469\,\frac{rad}{s^{2}}$

$I = \frac{\tau}{\alpha}$

$I = \frac{3\,N\cdot m}{36.469\,\frac{rad}{s^{2}} }$

$I = 0.0823\,N\cdot m\cdot s^{2}$

The moment of inertia of the motor is 0.0823 Newton-meter-square seconds.

5 0

3 years ago

Mr. Fuller assigned his science class a lab comparing the masses of objects to the nearest gram using a balance. The mass of a p

Tomtit [17]

The scale would need 10 aluminum cubes on one side. Figure out how many paper clips would be needed on the other side to balance this. You have to use more than one aluminum cube because you need to have enough cubes so that you get a whole number mass. 10 cubes gives you a total mass of 27 g for the aluminum.

5 0

3 years ago

The planet Mars has much less gravitational force that Earth. What would happen if you went to Mars?

vovangra [49]

gravitational force of planet exerted on its object near the surface is known as weight

so here we know that gravitational force of mars is much less than the gravitational force of Earth

So on the surface of mars the Weight of objects must be much less than the weight of object on surface of Earth

so here correct answer must be

<em>D. Your weight would decrease.</em>

6 0

3 years ago

4. What are 3 things that you can think of doing, that would reduce<br> your electricity bill?

Cloud [144]

Turn off standby appliances.
Install a smart thermostat.
Turn down your thermostat.
Buy efficient appliances.
Install a new boiler.
Wash clothes at a lower temperature.
Be smarter about water.
Invest in double glazing.

3 0

2 years ago

A 150 kg boy and his bike are traveling 12 m/s when he slams on his breaks and stop at his friend’s house. How much impulse is r

Nataly [62]

Answer:

J = 1800 kg-m/s

Explanation:

Given that,

Mass of a boy, m = 150 kg

Initial velocity of a boy, u = 12 m/s

Finally, it stops, v = 0

We need to find the impulse is required to produce this change in momentum. We know that impulse is equal to the change in momentum. So,

$J=m(v-u)\\\\=150\times (0-12)\\\\=-1800\ kg-m/s\\\\|J|=1800\ kg-m/s$

So, the impulse is equal to 1800 kg-m/s

4 0

3 years ago