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const2013 [10]
3 years ago
15

A CD player rotates at a variable speed so that a laser can scan pits and lands on the disk’s bottom surface at a constant tange

ntial speed of 1.2 m/s. The disk has a moment of inertia of 1.2 x 10-4 kg m2and the music is first detected when the laser is located 15 mm from the disk’s center. Assuming the disk started from rest, find the work done by the motor during this start-up.
Physics
1 answer:
LekaFEV [45]3 years ago
6 0

Answer:

W = 0.384 J

Explanation:

Work and energy in the rotational movement are related

    W = ΔK = K_{f} - K₀

    W = ½ I w_{f}² - 1 /2 I w₀²

where W isthe work, I is the moment of inertia and w angular velocity

With the system part of the rest the initial angular speed is zero (w₀ = 0)

The angular and linear quantities are related

    v = w r

    w = v / r

Let's replace

    W = ½ I (v / r)²

Let's calculate

    W = ½  1.2 10⁻⁴ 1.2² / (1.5 10⁻²)²

    W = 0.384 J

    W = 38.4 J

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Help! PROJECTILE PROBLEM: A 7500-kg rocket blasts off vertically from the launch pad with a constant upward acceleration of 2.25
dsp73
Here, 

height at failure, h1 = 525 m, 
upward acceleration, a = 2.25 m/s^2, 
velocity = v m/s, 
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SO, </span>
<span>
v^2 = 2*a*h = 2*2.25*525 = 2362.5 </span>
Now, acceleration, g = 9.8 m/s^2, 
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Hence, 
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a) </span>
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3 years ago
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Answer:

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2 years ago
A box is sliding down an incline tilted at a 11.1° angle above horizontal. The box is initially sliding down the incline at a sp
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Answer:s=0.68 m

Explanation:

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Speed of block(u)=1.6 m/s

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Using v^2-u^2=2as

Final velocity v=0

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3 years ago
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