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Oduvanchick [21]
3 years ago
11

How efficient is an incandescent light bulb?

Physics
1 answer:
hoa [83]3 years ago
6 0
That depends on what you want to use them for.

As sources of light, they are somewhere around 15% - 20% efficient.

As heaters, they are somewhere around 80% - 85% efficient.
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The graph shows how the vertical velocity of a parachutist changes from the moment the parachutist jumps from the aircraft until
Deffense [45]

Answer:

once the parachute is opened, the air resistance overwhelms the downward force of gravity. The net force and the acceleration on the falling skydiver is upward. ... The skydiver thus slows down. As the speed decreases, the amount of air resistance also decreases until once more the skydiver reaches a terminal velocity.

Explanation:

7 0
3 years ago
A 30 kg male emperor penguin under a clear sky in the Antarctic winter loses very little heat to the environment by convection;
yarga [219]

Answer:

Rate of energy loss by radiation is 28.31 Watt

Explanation:

Given that;

m = 30 kg

power p = 12 W

emissivity e = 0.97

Surface Area A = 0.56 m²

outside of the penguin's body  T = −22°C

surroundings Temperature Ts = -38°C

the rate of energy loss by radiation = ?

Now, using Stefan-Boltzmann law;

P = σeA [ T⁴ - Ts⁴ ]

Stefan's constant σ = 5.67 × 10⁻⁸

so we substitute

P = 5.67 × 10⁻⁸ × 0.97 ×  0.56  [ (-22 + 273 k)⁴ - (-38 + 273 k )⁴]

= 3.079944 × 10⁻⁸ [ 919325376]

=  28.31 Watt

the rate of energy loss by radiation is 28.31 Watt

8 0
3 years ago
Which of the following always occurs when a light ray reflects off a mirror? A.the speed of the light ray increases B. The direc
kakasveta [241]
<span>The angle at which the light ray strikes the mirror equals the angle at which it reflects. Its the first law of reflection.</span>
8 0
4 years ago
Read 2 more answers
the thermometer has its stem marked in millimeter instead of degree Celsius. the lower fixed point is 30mm and the upper fixed p
Lorico [155]

10°c

Explanation:

Given parameter;

Lower fixed point = 30mm

Upper fixed point = 180mm

Reading = 45mm

Unknown:

The degree celcuis temperature at 45mm = ?

Solution:

To solve this problem we simply compare the mm- scale to the celcius - scale that we know.

The upper fixed point is the boiling point of water

Lower fixed point is the freezing point of water

This shows that both the upper and lower fixed point of both thermometers are the same;

         mm-scale          °c scale

          180mm               100°c

            45mm                x

          30mm                  0°c

Solving;

                     \frac{x - 0}{100 -0} =  \frac{45 - 30 }{180- 30}

   x (150) = 100  x 15

   x = 10°c

learn more:

Temperature scales brainly.com/question/1603430

#learnwithBrainly

 

7 0
4 years ago
A shopping cart is given an initial velocity of 2 m/s and undergoes a constant acceleration of 4 m/s2. What is the magnitude of
Rasek [7]

Answer:

84 meters

Explanation:

Using these two kinematic equations : Vf= Vi +at and

D= [(Vi+Vf)/2]*t

Plugging in what we know into the first equation to solve for the Final velocity, you'll get Vf= 2 m/s + 4(m/s^2)*6s = 26m/s

plug time vi and vf into the second equation to solve for displacement.

6 0
3 years ago
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