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3 years ago

11

In a particular area of the country, electrical energy costs $0.12 per kilowatt-hour. (Round your answers, in dollars, to at lea

st two decimal places.) (a) How much does it cost to operate an old-style incandescent 100-W light bulb continuously for 24 hours? $ (b) A modern LED light bulb that emits as much visible light as a 100-W incandescent only draws 16.0 W of power. How much does it cost to operate this bulb for 24 hours? $ (c) A particular electric oven requires a potential difference of 220 V and draws 20.0 A of current when operating. How much does it cost to operate the oven for 5.30 hours? $

1 answer:

Delvig [45]3 years ago

7 0

Answer:

a) cost = $ 0.29 , b) cost = $ 0.046 , c) cost = $ 2.80

Explanation:

a) Let's find the energy consumed by this bulb, which is the product of the power and time

energy = P t

energy = 100 24 = 2400 W h

as the cost of energy is given in kWh we reduce this value

Energy = 2400 Wh (1 kW / 1000W)

Energy = 2.40 kWh

Calculate the cost of energy

cost = 0.12 2.40

cost = $ 0.288

cost = $ 0.29

b) energy = 16.0 24 = 384 Wh

we reduce to kWh

energy = 0.384 kWh

cost = 0.12 0.384

cost = $ 0.0461

cost = $ 0.046

c) let's find the power consumed by the oven

P = I V

P = 20.0 220

P = 4400 W

we look for the energy consumed

energy = 4400 5.30

energy = 23320 Wh

we reduce to kWh

energy = 23.32 kWh

we calculate the cost of this energy

cost = 0.12 23.32

cost = $ 2,798

cost = $ 2.80

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Answer:

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force of friction on base of ladder $F_R$

normal force on base of ladder $F_N$

From the free body diagram of the sketch you get 3 equations:

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Solving the equations gives:

$F_W = F_R\\ F_N = F_F + F_L\\ F_W = \frac{r_FF_F + 0.5r_LF_L}{r_L tan\alpha}$

a)

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b)

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Answer:

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