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andreyandreev [35.5K]
3 years ago
10

what is the percent efficiency of a light bulb that emits 14 joules of light for every 60 joules of electric energy thst enters

it?
Physics
1 answer:
jasenka [17]3 years ago
5 0
If you're using the bulb as a source of light, then it's. 14/60 = 23.3% efficient.
If you're using it to heat a bird nest or a hamster cage, then it's. 46/60 = 76.7% efficient !
It just depends on your point of view, and what you consider 'useful' output.
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The starship Enterprise approaches the planet Risa at a speed of 0.8c relative to the planet. On the way, it overtakes the inter
Alchen [17]

Answer:

<em>0.3c</em>

<em></em>

Explanation:

The speed of Enterprise relative to Risa is 0.8c

Relative speed of both ships as measured from Enterprise is 0.5c

therefore, relative speed of Astra to Enterprise is 0.8c - 0.5c = <em>0.3c</em>

<em>this is also the relative speed with which Astra approaches the planet Risa since Enterprise's speed was calculated relative to Risa.</em>

8 0
3 years ago
Una furgoneta circula por una carretera a 55km/h. Diez km atrás , un coche circula en el mismo sentido a 85km/h ¿ En cuanto tiem
statuscvo [17]

Answer:

t = 0.33h = 1200s

x = 18.33 km

Explanation:

If the origin of coordinates is at the second car, you can write the following equations for both cars:

car 1:

x=x_o+v_1t    (1)

xo = 10 km

v1 = 55km/h

car 2:

x'=v_2t    (2)

v2 = 85km/h

For a specific value of time t the positions of both cars are equal, that is, x=x'. You equal equations (1) and (2) and solve for t:

x=x'\\\\x_o+v_1t=v_2t\\\\(v_2-v_1)t=x_o\\\\t=\frac{x_o}{v_2-v_1}

t=\frac{10km}{85km/h-55km/h}=0.33h*\frac{3600s}{1h}=1200s

The position in which both cars coincides is:

x=(55km/h)(0.33h)=18.33km

6 0
3 years ago
A 69 kg zebra is traveling 7 m/s east. What is the zebra’s momentum? kg-m/s
Hitman42 [59]
Linear momentum is the product of mass and velocity. In this case, it is simply:
69\times 7 = 483 kg\cdot m/s
6 0
3 years ago
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The amplitude of wave-c is 1 meter.

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4 0
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In general, metalloids are slightly reactive.
algol [13]
Yes, in general, metalloids are slightly reactive.
6 0
3 years ago
Read 2 more answers
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