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2 years ago

Can someone explain the law of conservation of energy?

1 answer:

5 0

The law of conservation of energy is:

-- Energy can't be created or destroyed.

-- Energy can't just appear out of nowhere. If you suddenly have
more energy, then the 'extra' energy had to come from somewhere.

-- Energy can't just disappear. If you suddenly have less energy,
then the 'missing' energy had to go somewhere.
________________________________________

There are also conservation laws for mass and electric charge.
They say exactly the same thing. Just write 'mass' or 'charge'
in the sentences up above, in place of the word 'energy'.
________________________________________

And now I can tell you that the conservation laws for energy and mass
are actually one single law ... the conservation of mass/energy. That's
because we discovered about 100 years ago that mass can convert
into energy, and energy can convert into mass, and it's the total of BOTH
of them that gets conserved (can't be created or destroyed).

How much mass makes how much energy ?

The answer is E = m c² .

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A 60-W, 120-V light bulb and a 200-W, 120-V light bulb are connected in series across a 240-V line. Assume that the resistance o

gulaghasi [49]

A. 0.77 A

Using the relationship:

$P=\frac{V^2}{R}$

where P is the power, V is the voltage, and R the resistance, we can find the resistance of each bulb.

For the first light bulb, P = 60 W and V = 120 V, so the resistance is

$R_1=\frac{V^2}{P}=\frac{(120 V)^2}{60 W}=240 \Omega$

For the second light bulb, P = 200 W and V = 120 V, so the resistance is

$R_1=\frac{V^2}{P}=\frac{(120 V)^2}{200 W}=72 \Omega$

The two light bulbs are connected in series, so their equivalent resistance is

$R=R_1 + R_2 = 240 \Omega + 72 \Omega =312 \Omega$

The two light bulbs are connected to a voltage of

V = 240 V

So we can find the current through the two bulbs by using Ohm's law:

$I=\frac{V}{R}=\frac{240 V}{312 \Omega}=0.77 A$

B. 142.3 W

The power dissipated in the first bulb is given by:

$P_1=I^2 R_1$

where

I = 0.77 A is the current

$R_1 = 240 \Omega$ is the resistance of the bulb

Substituting numbers, we get

$P_1 = (0.77 A)^2 (240 \Omega)=142.3 W$

C. 42.7 W

The power dissipated in the second bulb is given by:

$P_2=I^2 R_2$

where

I = 0.77 A is the current

$R_2 = 72 \Omega$ is the resistance of the bulb

Substituting numbers, we get

$P_2 = (0.77 A)^2 (72 \Omega)=42.7 W$

D. The 60-W bulb burns out very quickly

The power dissipated by the resistance of each light bulb is equal to:

$P=\frac{E}{t}$

where

E is the amount of energy dissipated

t is the time interval

From part B and C we see that the 60 W bulb dissipates more power (142.3 W) than the 200-W bulb (42.7 W). This means that the first bulb dissipates energy faster than the second bulb, so it also burns out faster.

7 0

2 years ago

Scientists have discovered convection currents inside Earth. Explain how these convection currents move and what layer(s) they o

fgiga [73]

Answer:

I don't know what to do

Explanation:

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3 years ago

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What type of electromagnetic wave does a light bulb and a radio antenna release?

andrew-mc [135]

I believe that a light bulb releases visible light and a radio antenna releases a radio waves

4 0

3 years ago

Which of the following describes pressure in a fluid?

PtichkaEL [24]

<span>D. Pressure increases with increasing depth.

This occurs because there is more weight above you to increase the pressure.
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3 years ago

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How are longitudinal and transverse waves different?

Natalija [7]

Answer:

A longitudinal wave is a wave where the movement of the medium is in the same direction as the wave. On the other hand, a transverse wave is a wave where the movement of the medium is at a right angle to the wave direction.

Explanation:i got this right on a quiz so i know its right

3 0

3 years ago