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4 years ago

A pulley system operates with 40% efficiency. if the work put in is 200 joules, how much useful work is produced?

2 answers:

8 0

<span>1. </span><span>Efficiency is the measure of how efficient a process is. It is used to assess the ability of a process in avoiding waste energy, materials, money and time in doing a desirable output. It is calculated as;

Efficiency = useful energy ouput / total energy input</span>

<span>.40 = useful work / 200</span>

<span>useful work = 80 joules</span>

FinnZ [79.3K]4 years ago

5 0

Answer:

The useful work produced by a pulley system is 80 Joules.

Explanation:

Efficiency is a measure of how much work is preserved in a process. The formula for efficiency is the energy output, divided by the energy input, expressed as a percentage. A perfect process would have an efficiency of 100%.

η = efficiency (Greek letter "eta")

Wo = the work or energy produced by a process. Units are Joules (J).

Wi = the work or energy put in to a process. Units are Joules (J).

$n = \frac{Wo}{Wi}$

$0.4 = \frac{Wo}{200J}$

Wo = 0.4*200J

Wo = 80 J

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A sled drops 50 meters in height on a hill. The mass of the rider and sled is 70 kg and the sled is going 10 m/s at the bottom o

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Answer:

Efficiency = 10.2 %

Explanation:

Given the following data;

Mass = 70 kg

Height = 50 m

Velocity = 10 m/s

We know that acceleration due to gravity is equal to 9.8 m/s².

To find the efficiency of energy conversion from potential to kinetic;

First of all, we would determine the potential energy;

P.E = mgh

P.E = 70 * 9.8 * 50

P.E = 34300 J

For the kinetic energy;

K.E = ½mv²

K.E = ½ * 70 * 10²

K.E = 35 * 100

K.E = 3500

Therefore, Input energy, I = 34300 J

Output energy, O = 3500 J

Next, we find the efficiency;

Efficiency = O/I * 100

Substituting into the formula, we have;

Efficiency = 3500/34300 * 100

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Efficiency = 10.2 %

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Answer:

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Explanation:

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3 years ago

Wavelength is measured in hertz true or false?

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3 years ago

A 100 kilogram person acquires a velocity of 15 meters per second down a ski slope.What is the skier's kinetic energy?

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11250J

Explanation:

Given parameters:

Mass of the person = 100kg

Velocity = 15m/s

Unknown:

Kinetic energy = ?

Solution:

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Kinetic energy = $\frac{1}{2}$ m v²

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Kinetic energy brainly.com/question/6536722

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3 years ago

When he reaches the bottom, 4.2 m below his starting point, his speed is 2.2 m/s . By how much has thermal energy increased duri

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Complete question:

A fireman of mass 80 kg slides down a pole. When he reaches the bottom, 4.2 m below his starting point, his speed is 2.2 m/s. By how much has thermal energy increased during his slide?

Answer:

The thermal energy increased by 3,099.2 J

Explanation:

Given;

mass of the fireman, m = 80 kg

initial position of the fireman, hi = 4.2 m

final speed, v = 2.2 m/s

The change in the thermal energy is calculated as;

ΔE + (K.Ef - K.Ei) + (Uf - Ui) = 0

where;

ΔE is the change in the thermal energy

K.Ef is the final kinetic energy

K.Ei is the initial kinetic energy

Uf is the final potential energy

Ui is the initial potential energy

$\Delta E_{th} + (\frac{1}{2} mv_f^2 - \frac{1}{2} mv_i^2) + (mgh_f - mgh_i)=0\\\\initial \ velocity, \ v_i = 0\\final \ height , \ h_f = o\\\\\Delta E_{th} + (\frac{1}{2} mv_f^2) + ( - mgh_i)=0\\\\\Delta E_{th} + \frac{1}{2} mv_f^2 - mgh_i = 0\\\\\Delta E_{th} =mgh_i - \frac{1}{2} mv_f^2\\\\\Delta E_{th} = 80 \times 9.8 \times 4.2 \ \ - \ \ \frac{1}{2} \times 80 \times (2.2)^2 \\\\\Delta E_{th} = 3292.8 \ J \ - \ 193.6 \ J\\\\\Delta E_{th} = 3,099.2 \ J$

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