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3 years ago

13

A man pushes down on a lever with 45 N and the lever moves 1.5 meters. The other end of the lever lifts a 87.6 N box .4 meters.

What is the efficiency of the lever?

1 answer:

AysviL [449]3 years ago

4 0

The input work = Force x distance
So I/P = 45 x 1.5 = 67.5 N.m

The output work = Force x distance
So, O/P = 87.6 x 0.4 = 35.04 N.m

Efficiency = (output work / Inputwork) x 100
= ( 35.04/67.5) x100

Efficiency = 51.91 %

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and $\phi _{i}$ is the initial magnetic flux

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Where $B$ is the magnetic field

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and $\theta$ is the angle between the magnetic field and the area.

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$\phi_{i} = (1.5)(0.0225\pi)$

( NOTE: $cos (0^{o}) = 1$ )

$\phi_{i} = 0.03375\pi$ Wb

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The field pointed upwards, that is $\theta = 90^{o}$ . Since $cos (90^{o}) = 0$

Then

$\phi_{f} = 0$

Hence,

$\Delta \phi = 0- 0.03375\pi$

$\Delta \phi = - 0.03375\pi$

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$\Delta t = 2.8 ms = 2.8 \times 10^{-3} s$

Here, $N$ = 1

Hence,

$Emf = -N\frac{\Delta \phi}{\Delta t}$ becomes

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