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2 years ago

Why do you think lightning is so dangerous if it strikes a person?

Physics

1 answer:

antiseptic1488 [7]2 years ago

5 0

Do you remember the old fashioned flashlights, before there were LEDs ?

They had two or three heavy batteries in the tube, and one little tiny glass light bulb in the middle of the little headlight in the front. When the batteries were fresh, that little light bulb gave out a nice bright beam of light, and drew about 0.7 Amperes from the batteries. That's the number I want you to remember for a couple of minutes: Flashlight bulb, 0.7 Amperes.

-- The wiring (nerves) that operate your heart can go haywire, and your heart can stop or go crazy, if 0.015 Amp of current or more happens to pass close by it.

-- The muscles in your arms or legs, or your diaphragm that makes you breathe, can lock up so that you can't control them, if 0.1 Amp of current or more happens to pass by them. If that current is 0.5 Amp or more and passes close to a muscle, the muscle can lock up so violently that it breaks the arm- or leg-bone that it's attached to.

Lightning is electric current flowing between a cloud and the ground. If anything is in the path it wants, it just flows right on through.

Lightning may flow in either direction ... up to the cloud or down to the ground. It really doesn't make any difference. The effects are the same, on anything it decides to flow through.

The current in a typical, average lightning bolt is 30,000 Amperes. A lot of them are bigger.

Current flowing through anything causes heat to be generated.

The more current = the more heat.

-- Lightning flowing through the wall of a house generates enough heat inside the wall to make the wall explode.

-- Lightning flowing through the juice inside a tree generates enough heat to boil the tree juice, and explode the tree.

-- Lightning flowing through the air heats a skinny tube of air so hot and so fast that the air explodes. That makes a strong sound wave in the air, that can be heard from miles away. It's called "thunder".

-- A person is made of lots of nice soft, moist, mushy stuff, water, juices, and air. A thousand Amperes flowing through it all can do a fast, efficient, complete job of heating it, boiling it, cooking it, exploding it, and tearing it to pieces.

Sounds dangerous to me.

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A satellite is launched to orbit the Earth at an altitude of 3.25 107 m for use in the Global Positioning System (GPS). Take the

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Answer:Orbital period =21.22hrs

Explanation:

given that

mass of earth M = 5.97 x 10^24 kg

radius of a satellite's orbit, R= earth's radius + height of the satellite

6.38X 10^6 + 3.25 X10^7 m =3.89 X 10^7m

Speed of satellite, v= $\sqrt GM/R$

where G = 6.673 x 10-11 N m2/kg2

V= \sqrt (6.673x10^-11 x 5.97x10^ 24)/(3.89 X 10^ 7m)

V =10,241082.2

v= 3,200.2m/s

a) Orbital period

$\sqrt GM/R$ = $\frac{2\pi r}{T}$

V= $\frac{2\pi r}{T}$

T= 2 $\pi$ r/ V

= 2 X 3.142 X 3.89 X 10^7m/ 3,200.2m/s

=76,385.1 s

60 sec= 1min

60mins = 1hr

76,385.1s =hr

76,385.1/3600=21.22hrs

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3 years ago

A car travels around a curve. What can you say about the centripetal force if the velocity is tripled?

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Answer:

F = M a = M v^2 / R

If v is increased by three the force will be increased by nine,

C) is correct

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2 years ago

Question 17 A sample of iron is put into a calorimeter (see sketch at right) that contains of water. The iron sample starts off

ivanzaharov [21]

Complete Question:

A 59.1 g sample of iron is put into a calorimeter (see sketch attached) that contains 100.0 g of water. The iron sample starts off at 85.0 °C and the temperature of the water starts off at 23.0 °C. When the temperature of the water stops changing it's 27.6 °C. The pressure remains constant at 1 atm.

Calculate the specific heat capacity of iron according to this experiment. Be sure your answer is rounded to the correct number of significant digits

(Question attached)

Answer:

$c_{iron}=0.568 J/kg.\°C$

$c_{iron}=0.6 J/kg.\°C$ (rounded to 1 decimal place)

Explanation:

A calorimeter is used to measure the heat of chemical or physical reactions. The example given in the question is using the calorimeter to determine the specific heat capacity of iron.

When the system reaches equilibrium the iron and water will be the same temperature, $T_{e}$ . The energy lost from the iron will be equal to the energy gained by the water. It is assumed that the only heat exchange is between the iron and water and no exchange with the surroundings.

$Q=mc(T_{e}-T_{initial})$ (Eq 1)

$-Q_{iron}=Q_{water}$ (Eq 2)

Water:

$m_{water}=100.0 g, c_{water}=4.186 J/kg.\°C, T_{initial,water}=23 \°C, T_{e}=27.6 \°C$

Iron:

$m_{iron}=59.1 g, c_{iron} = ? J/kg.\°C, T_{initial,iron}=85 \°C, T_{e}=27.6 \°C$

Substituting Eq 1 into Eq 2 and details extracted from the question:

$-m_{iron}c_{iron}(T_{iron,e}-T_{initial})=m_{water}c_{water}(T_{water,e}-T_{initial})$

$-59.1*c_{iron}(27.6-85)=100.0*4.186(27.6-23)$

$c_{iron}=0.568 J/kg.\°C$

$c_{iron}=0.6 J/kg.\°C$

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3 years ago