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kolezko [41]
3 years ago
8

The electric motor of a model train accelerates the train from rest to 0.685 m/s in 21.5 ms. The total mass of the train is 875

g. Find the minimum power delivered to the train by electrical transmission from the metal rails during the acceleration.
Physics
1 answer:
Natali [406]3 years ago
8 0

Answer:

P=9.58 W

Explanation:

According to Newton's second law, and assuming friction force as zero:

F_m=m.a\\F_m=0.875kg*a

The acceleration is given by:

a=\frac{\Delta v}{t}\\a=\frac{0.685m/s}{21.5*10^{-3}s}\\\\a=31.9m/s^2

So the force exerted  by the motor is:

F_m=0.875kg*31.9m/s^2\\F_m=27.9N

The work done by the motor is given by:

W_m=F_m*d\\\\d=\frac{1}{2}*a*t^2\\d=\frac{1}{2}*31.9m/s^2*(21.5*10^{-3}s)^2\\\\d=7.37*10^{-3}m

W_m=27.9N*7.37*10^{-3}m\\W_m=0.206J

And finally, the power is given by:

P=\frac{W_m}{t}\\P=\frac{0.206J}{21.5*10^{-3}s}\\\\P=9.58W

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A merry-go-round is shaped like a uniform disk and has moment of inertia of 50,000 kg m 2 . It is rotating so that it has an ang
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Answer:

r = 20 m

Explanation:

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10000 kg.m²/s = mr(2 m/s)

m r = (10000 kg.m²/s)/(2 m/s)

m r = 5000 kg.m   ------------- equation 1

Now, the moment of inertia of a solid uniform disc about its axis through its center is given as:

I = (1/2) m r²

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I = moment of inertia = 50000 kg.m²

Therefore,

50000 kg.m² = (1/2)(m r)(r)

using equation 1, we get:

50000 kg.m² = (1/2)(5000 kg.m)(r)

(50000 kg.m²)/(2500 kg.m) = r

<u>r = 20 m</u>

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2 years ago
Ball A was carried to the top of a hill in a straight line, while ball B was carried in a longer, zigzag path. At the top of the
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3 years ago
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The intensity I of light varies inversely as the square of the distance D from the source. If the intensity of illumination on a
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The intensity on a screen 20 ft from the light will be 0.125-foot candles.

<h3>What is the distance?</h3>

Distance is a numerical representation of the length between two objects or locations.

The intensity I of light varies inversely as the square of the distance D from the source;

I∝(1/D²)

The ratio of the intensity of the two cases;

\rm \frac{I_1}{I_2} =(\frac{D_2}{D_1} )^2\\\\ \rm \frac{2}{I_2} =(\frac{20}{5} )^2\\\\ \frac{2}{I_2} =4^2 \\\\ I_2= \frac{2}{16} \\\\  I_2= 0.125 \ foot-candles

Hence, the intensity on a screen 20 ft from the light will be 0.125 foot-candles

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6 0
2 years ago
Mary and her younger brother Alex decide to ride the 26 ft diameter carousel at the State Fair. Mary sits on one of the horses i
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Answer:

a_M=1.92a_A

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\omega_M=\omega_A = Angular speed

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Ratio of centripetal acceleration is given by

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Mary's centripetal acceleration is 1.92 times the centripetal acceleration of Alex

8 0
3 years ago
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