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3 years ago

If something is 50% efficient, how many joules of wasted energy will there be if 750J of energy is put in?

Physics

1 answer:

evablogger [386]3 years ago

5 0

Answer:

375J of wasted energy

Explanation:

Efficiency=work output/work input×100%

50=w.o/750×100

750×50=100w.o

w.o=750×50/100

w.o=75×5

w.o=375J

Wasted energy=750J-375J

=375J

Aliter

If the machine is 50% efficient then it is also 50% inefficient

50%×750J=375J

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3 years ago

An infinitely long line of charge has a linear charge density of 7.50×10^−12 C/m . A proton is at distance 14.5 cm from the line

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Answer:

10.22 cm

Explanation:

linear charge density, λ = 7.5 x 10^-12 C/m

distance from line, r = 14.5 cm = 0.145 m

initial speed, u = 3000 m/s

final speed, v = 0 m/s

charge on proton, q = 1.6 x 10^-19 C

mass of proton, m = 1.67 x 10^-27 kg

Let the closest distance of proton is r'.

The potential due t a line charge at a distance r' is given by

$V=-2K\lambda ln\left (\frac{r'}{r} \right )$

where, K = 9 x 10^9 Nm^2/C^2

W = q V

By use of work energy theorem

Work = change in kinetic energy

$qV = 0.5m(u^{2}-v^{2})$

By substituting the values, we get

$V=\frac{mu^{2}}{2q}$

$-2K\lambda ln\left ( \frac{r'}{r} \right )=\frac{mu^{2}}{2q}$

$- ln\left ( \frac{r'}{r} \right )=\frac{mu^{2}}{4Kq\lambda }$

$- ln\left ( \frac{r'}{r} \right )=\frac{1.67 \times 10^{-27}\times 3000\times 3000}{4\times 9\times 10^{9}\times 1.6\times 10^{-19}\times 7.5\times 10^{-12} }$

$- ln\left ( \frac{r'}{r} \right )=0.35$

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$\frac{r'}{r} =0.7047$

r' = 14.5 x 0.7047 = 10.22 cm

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4 years ago

A person walks into a room that has, on opposite walls, two plane mirrors producing multiple images. Find the distances from the

worty [1.4K]

Answer:

Explanation:

When the person stands 5.80 ft from the mirror of the wall.

a) The first image is found by multiplying the distance of the left mirror to the person.

i.e.

2 × 5.80 = 11.6 ft

b) The second image is deduced by the addition of the distance of the first image with the distance created by the right mirror.

i.e.

(2 × 13.7 ) + 11.6

= 39 ft

c) The third image is acquired by the addition of the image presented by the left mirror and the image presented by the right mirror.

(2 × 5.80) + 39

= 50.6 ft

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3 years ago

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3 years ago

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Answer

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