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3 years ago

13

. Calculate the work done by an elevator as it lifts 12 occupants up 21 floors (76.8 meters) at a constant speed. The average ma

ss of the occupants is 62.8 kg. (show work)

1 answer:

ratelena [41]3 years ago

6 0

Answer:

W = 4832

Explanation:

Given:

Force = 62.8 Kg

Distance = 76.8 m

Find :

work done = ?

Formula :

W = Fd

Solution:

W = Fd

W =(62.8 kg)(76.8 m)

= 4832 J

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Sound at 70 dB is 70 dB louder than the human reference level. That's 10⁷ times as much as the reference sound power.

Sound at 73 dB is 73 dB louder than the human reference level. That's 10⁷.³ or 2 x 10⁷ times as much as the reference sound power.

Sound at 80 dB is 80 dB louder than the human reference level. That's 10⁸ or 10 x 10⁷ times as much as the reference sound power.

Now we can adumup:

Intensity of all 3 sources = (10⁷) + (2 x 10⁷) + (10 x 10⁷)

Intensity = (13 x 10⁷) times the sound power reference intensity.

Intensity in dB = 10 log (13 x 10⁷) = 10 (7 + log(13)

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<em>______________________________________</em>

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Explain velocity ratio. Explain and define the efficiency of a machine

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To test the performance of its tires, a car

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<u>Answer</u>:

The coefficient of static friction between the tires and the road is 1.987

<u>Explanation</u>:

<u>Given</u>:

Radius of the track, r = 516 m

Tangential Acceleration $a_r$ = 3.89 m/s^2

Speed,v = 32.8 m/s

<u>To Find:</u>

The coefficient of static friction between the tires and the road = ?

<u>Solution</u>:

The radial Acceleration is given by,

$a_{R = \frac{v^2}{r}$

$a_{R = \frac{(32.8)^2}{516}$

$a_{R = \frac{(1075.84)}{516}$

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Now the total acceleration is

$\text{ total acceleration} = \sqrt{\text{(tangential acceleration)}^2 +{\text{(Radial acceleration)}^2$

=> $= \sqrt{ (a_r)^2+(a_R)^2}$

=> $\sqrt{ (3.89 )^2+( 2.085)^2}$

=> $\sqrt{ (15.1321)+(4.347)^2}$

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Now the coefficient of static friction is

$\mu =\frac{f}{W}$

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$\mu =\frac{ma}{mg}$

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lyudmila [28]

Answer: Angle 59 degree

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Substitute all the parameters into the formula

1/1.5 = sin 35/sinØ2

Cross multiply

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Ø2 = sin^-1(0.860)

Ø2 = 59.36 degree

Ø2 = 59 degree ( approximately)

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