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3 years ago

If the work put into a lever is 25.0 joules and the work done by the lever is 20.0 joules, what is the efficiency of the lever?

Physics

2 answers:

Kisachek [45]3 years ago

6 0

Answer:

Efficiency of the lever is 80 %.

Explanation:

Given that, if the work put into a lever is 25.0 joules and the work done by the lever is 20.0 joules. We need to find the efficiency of the lever. The mathematical expression for the efficiency is given by :

$\eta=\dfrac{W_o}{W_i}\times 100$

Where

$W_o\ and\ W_i$ are output and input work respectively.

$\eta=\dfrac{20}{25}\times 100$

$\eta=80\%$

So, the efficiency of the lever is 80 %. Hence, this is the required solution.

Liula [17]3 years ago

5 0

The efficiency is Wout/Win = 25/20

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Answer:

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Suppose that a siren makes a sound reaching 120 decibels, but a wolf’s howl only reaches 90 decibels. 120 dB is how many times l

MakcuM [25]

Answer:

I₁/I₂ = 1000

Thus, the sound of siren is 1000 times louder than the sound of wolf's howl.

Explanation:

First, we need to calculate the intensity of both the sounds. The formula for sound level is given as:

L = 10 log[I/I₀]

where,

L = Sound Level in dB

I = Intensity of sound

I₀ = Reference intensity = 10⁻¹² W/m²

FOR SOUND OF SIREN:

L = 120 dB

I = I₁ = ?

Therefore,

120 = 10 log[I₁/10⁻¹²]

log[I₁/10⁻¹²] = (120)/10

log[I₁/10⁻¹²] = 12

I₁/10⁻¹² = 10¹²

I₁ = (10¹²)(10⁻¹²)

I₁ = 1

FOR SOUND OF WOLF'S HOWL:

L = 90 dB

I = I₂ = ?

Therefore,

90 = 10 log[I₂/10⁻¹²]

log[I₂/10⁻¹²] = (90)/10

log[I₂/10⁻¹²] = 9

I₂/10⁻¹² = 10⁹

I₂ = (10⁹)(10⁻¹²)

I₂ = 10⁻³

Now, we divide the intensities:

I₁/I₂ = 1/10⁻³

I₁/I₂ = 10³

I₁/I₂ = 1000

Thus, the sound of siren is 1000 times louder than the sound of wolf's howl.

4 0

3 years ago

A bicyclist is traveling at +25 m/s when he begins to decelerate at -4 m/s2. How fast is he traveling after 5 seconds?

Karo-lina-s [1.5K]

Answer:

The bicyclist goes at 5 m/s

Explanation:

Motion With Constant Acceleration

It's a type of motion in which the velocity of an object changes uniformly in time.

The equation that rules the change of velocities is:

$v_f=v_o+at$

Where:

a = acceleration

vo = initial speed

vf = final speed

t = time

It's given a bicyclist is traveling at v0=+25 m/s and decelerates at $a=-4\ m/s^2$ . We are required to calculate the speed after t=5 seconds.

Applying the formula:

$v_f=25+(-4)*5$

$v_f=25-20=5$

$v_f=5\ m/s$

The bicyclist goes at 5 m/s

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3 years ago

(15 points)

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Answer:

1. Decrease

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2. The more the pollution effects them negatively, the more the population will die off.

3. The decrease of food may kill the population, but the increase of food does not effect the birth rate of the population.

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When 16.6 V is applied to a capacitor, it stores an energy of 8.15 x 10-4 J. How much charge is on the plates?

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