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3 years ago

Power lifter Paul lifts a 700.0kg barbell 2.00m in 0.400s. How much power did Paul develop?

2 answers:

6 0

   Work = (force) x (distance.

The force required to lift the load is its weight.

   Weight = (mass) x (gravity)

so Work = (mass) x (gravity) x (distance)

Now Power = (work) / (time)

so Power = (mass) x (gravity) x (distance) / (time)

= (700kg) x (9.8 m/s²) x (2 m) / (0.4 sec)

      = ( 700 x 9.8 x 2) / (0.4) (kg-m²/sec²) / (sec)

      =    ( 34,300 )    (joule) / (sec)

= 34,300 watts .

This is one of those exercises where the math and the physics
are air-tight and bullet-proof but the answer is absurd.

34,300 watts is about 46 horsepower. I don't care how many
Wheaties Power Lifter Paul had for breakfast today, he is NOT
snatching a barbell that weighs 1,543 pounds (0.77 ton !)
to the height of the top of his head in less than 1/2 second !

yawa3891 [41]3 years ago

3 0

34,335 W
P= mgh/t
P=700*2*9.81/.4

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Answer:

2 is the numerical answer.

Explanation:

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3 years ago

A see-saw is balanced on a pivot with two children on it. One child is sitting 1.5 m to the left of the pivot and has a mass of

Lorico [155]

Answer:

Explanation:

Remark

This is a second class lever. It is much more efficient than the fishing pole problem. All distances are measured from the pivot in these kinds of questions.

Givens

d1 = 1.5

d2 = ?

m1 = 50 kg

m2 = 30 kg

The lighter child will have to sit further away from the pivot to make the two conditions equal.

Formula

d1*m1 = d2*m2

1.5*50 = d2 * 30

75 = 30 * d2

75/30 = d2

d2 = 2.5

Remark

Notice that the distance is longer for the lighter child. The fact that these are masses and not forces does not matter, but you should take note of it. There is a difference between masses and forces. See the fishing pole problem.

Answer to the multiple Choice question. No motion on this kind of problem means equal moments. The answer is D

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3 years ago

Number of conducting plates of a multiplate capacitor is 5. The no. Of capacitors is

Ivahew [28]

Answer:

4 capacitors

Explanation:

Given

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