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3 years ago

Two lamps rated 60W; 240V and 100W, 240Vrespectively are connected in series to a 240V power source. Calculate;

Physics

1 answer:

nikdorinn [45]3 years ago

7 0

Answer:

See the answers below.

Explanation:

The total power of the circuit is equal to the sum of the powers of each lamp.

$P=60+100\\P=160 [W]$

Now we have a voltage source equal to 240 [V], so by means of the following equation we can find the current circulating in the circuit.

$P=V*I$

where:

P = power [W]

V = voltage [V]

I = current [amp]

$I = P/V\\I=160/240\\I=0.67 [amp]$

So this is the answer for c) I = 0.67 [amp]

We know that the voltage of each lamp is 240 [V]. Therefore using ohm's law which is equal to the product of resistance by current we can find the voltage of each lamp.

$V=I*R$

where:

V = voltage [V]

I = current [amp]

R = resistance [ohms]

Therefore we replace this equation in the first to have the current as a function of the resistance and not the voltage.

$P=V*I\\and\\V = I*R\\P = (I*R)*I\\P=I^{2}*R$

$60 = (0.67)^{2}*R\\R_{60}=133.66[ohm] \\and\\100=(0.67)^{2} *R\\R_{100}=100/(0.66^{2} )\\R_{100}=225 [ohm]$

The effective resistance of a series circuit is equal to the sum of the resistors connected in series.

$R = 133.66 + 225\\R = 358.67 [ohms]$

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If the wavelength of an s-wave is 23,000 m, and its speed 4500 m/s, what is its frequency?

wolverine [178]

Answer:

5 metre.

Explanation:

Wavelength = Velocity / Frequency

= 23,000/ 4,500

= 5 metre.

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3 years ago

Find mass when kinetic energy is 1.6 J and velocity is 0.2 m/s

klio [65]

Answer:

4kg

Explanation:

Given parameters:

Kinetic energy = 1.6J

Velocity = 0.2m/s

Unknown:

Mass of the body = ?

Solution:

The kinetic energy of a body is the energy due to the motion of the body.

It is mathematically expressed as;

Kinetic energy = $\frac{1}{2}$ m v²

m is the mass

v is the velocity

1.6 = $\frac{1}{2}$ x 0.2 x v²

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3 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

Which two pieces of evidence most directly support the idea that the universe is expanding from one original point?

Fudgin [204]

The redshift of light from galaxies and the uniform distribution of cosmic background radiation

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4 years ago

Read 2 more answers

Suppose that in a lightning flash the potential difference between a cloud and the ground is 1.3×109 V and the quantity of charg

Georgia [21]

Answer:

A) ΔU = 3.9 × 10^(10) J

B) v = 8420.75 m/s

Explanation:

We are given;

Potential Difference; V = 1.3 × 10^(9) V

Charge; Q = 30 C

A) Formula for change in energy of transferred charge is given as;

ΔU = QV

Plugging in the relevant values gives;

ΔU = 30 × 1.3 × 10^(9)

ΔU = 3.9 × 10^(10) J

B) We are told that this energy gotten above is used to accelerate a 1100 kg car from rest.

This means that the initial potential energy will be equal to the final kinetic energy since all the potential energy will be converted to kinetic energy.

Thus;

P.E = K.E

ΔU = ½mv²

Where v is final velocity.

Plugging in the relevant values;

3.9 × 10^(10) = ½ × 1100 × v²

v² = [7.8 × 10^(8)]/11

v² = 70909090.9090909

v = √70909090.9090909

v = 8420.75 m/s

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3 years ago