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ryzh [129]
3 years ago
15

A boy is playing with a ball of mass 72g attached to a string. He is moving it at constant speed in a horizontal circle of radiu

s 0.9m. a. State the net work done on the ball in one complete revolution. (1) b. The tension in the string is 60N. Determine the angular velocity of the ball. (4) c. Calculate the time it takes for the ball to complete 20 revolutions. (2)
Physics
1 answer:
irina [24]3 years ago
3 0

Answer:

Explanation:

radius of circle r = 0.9 m.

(a ) In a motion on circular path , work done is zero because force ( centripetal force ) acts perpendicular to displacement .

( b )

Tension in string T = m ω²r

Putting the values

60 = .072 x ω² x 0.9

ω² = 926

ω = 30.4 rad /s

angle made in 20 revolutions θ = 20 x 2π = 126.6 rad

time taken = θ / ω

= 126.6 / 30.4

= 4.16 s .

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Answer:

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Explanation:

This is because, since the two sources of sound have the same frequency and are separated by a distance, d = 10 mm, there would be successive points of constructive and destructive interference.

Since their frequencies are similar, we should have beats of high and low frequency.

So, at points of low frequency, the amplitude of the wave is smallest and there is destructive interference. The frequency at this point is the difference between the frequencies from both speakers. Since the frequency from both speakers is 400 Hz, we have, f - f' = 400 Hz - 400 Hz = 0 Hz. So, the volume of the sound is low(zero) at these points.

Also, at points of high frequency, the amplitude of the wave is highest and there is constructive interference. The frequency at this point is the sum between the frequencies from both speakers. Since the frequency from both speakers is 400 Hz, we have, (f + f') = 400 Hz + 400 Hz = 800 Hz. So, the volume of the sound is high at these points.

So, as you wander around the room, I should hear points of high and low sound across the room.

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3 years ago
How long would it take a 4,560 watt motor to raise a 166 kg piano to an apartment window
IrinaK [193]

Answer:

Explanation:

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t=\frac{(1600)(15)}{4560} so

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Explanation:

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