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3 years ago

Can you help me on this please

Physics

1 answer:

Vikentia [17]3 years ago

8 0

Answer: the water level would rise since the pebble displaces minimal water compared to the boat.

Explanation:..........

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A certain brand of hot dog cooker works by applying a potential difference of 120 V across opposite ends of a hot dog and allowi

Whitepunk [10]

Answer: 43s

Explanation:

The stored energy across a plate can be measured by calculating the electric charge and the potential difference. Also, the quantity of electricity can be measured by multiplying the current in the circuit with the time taken.

Given

Potential difference, V = 120 v

Current, I = 11.5 A

Energy, E = 59 kJ

Remember,

E = QV, so that

Q = E/V

Q = 59000/120

Q = 491.67 C

Q = IT

491.67 = 11.5*t

t = 491.67/11.5

t = 42.75s ~ 43s

Time taken to cook the 3 hot dogs simultaneously is 43s

5 0

3 years ago

Even when shut down after a period of normal use, a large commercial nuclear reactor transfers thermal energy at the rate of 150

Phoenix [80]

Answer:

The temperature of the core raises by $2.8^{o}C$ every second.

Explanation:

Since the average specific heat of the reactor core is 0.3349 kJ/kgC

It means that we require 0.3349 kJ of heat to raise the temperature of 1 kg of core material by 1 degree Celsius

Thus reactor core whose mass is $1.60\times 10^{5}kg$ will require

$0.3349\times 1.60\times 10^{5}kJ\\\\=0.53584\times 10^{5}kJ$

energy to raise it's temperature by 1 degree Celsius in 1 second

Hence by the concept of proportionately we can infer 150 MW of power will increase the temperature by

$\frac{150\times 10^{6}}{0.53584\times 10^{8}}=2.8^{o}C/s$

5 0

3 years ago

Ecology is the study of

Anettt [7]

Answer:

Organisms and their environment

8 0

3 years ago

5. A stream of air at 12 bar and 900 K is mixed with another stream of air at 2 bar and 400 K with 2 times the mass flowrate. If

Softa [21]

Answer:

The anserrs to the question are

(a) The temperature would be 566.67 K and

(b) The pressure of the resulting air stream is 14 bar

Explanation:

Here the two streams of gases meet ad form a single stream

The steady-flow energy equation can be implemented at the mixing point of the to streams as follows

mₐhₐ₁ + mₙ hₙ₁ + Q° + W° = mₐhₐ₂ + mₙhₙ₂

Where the flow is adiabatic, we have

Q = 0 and W = 0 hence

mₐhₐ₁ + mₙ hₙ₁ = mₐhₐ₂ + mₙhₙ₂ where h = cp×T we have

mₐcpₐ×Tₐ + mₙcpₙ×Tₙ = mₐcpₐ×T + mₐcpₙ×T

Therefore the final temperature T is given by

$T = \frac{m_ac_{pa}T_a + m_nc_{pn}T_n}{m_ac_{pa} + m_nc_{pn}}$ for the same kind of gas cpₐ =cpₙ therefore

$T = \frac{m_aT_a + m_nT_n}{m_a + m_n}$ where mₐ and mₙ are mass flow rate

Therefore we have where Tₐ = = 900 K and Tₙ = 400 K and mₙ = 2mₐ gives

$T = \frac{m_a*900 + 2*m_a*400}{m_a + 2*m_a}$ = $T = \frac{900 + 800}{1 + 2}$ = 1700/3 = 566.67 K

From Dalton's law, the total pressure of a mixture of gases is equal to the sum of the partial pressures of the components of the mixture

Therefore the total pressure of the combined stream = pₐ + pₙ = p

= 12 bar + 2 bar = 14 bar

Stream pressure = 14 bar

4 0

3 years ago

A solar panel is used to recharge a battery. The solar panel produces 0.80 W of electrical power. The panel is 20% efficient. Wh

Vlad [161]

Answer:

Input power, Ip = 4 Watts

Explanation:

Given the following data;

Power output = 0.8 Watts

Efficiency = 20%

To find the power input of the sunlight onto the solar panel;

Mathematically, the efficiency of a machine is given by the formula;

$Efficiency = \frac {Out-put \; power}{In-put \; power} * 100$

Substituting into the formula, we have;

$20 = \frac {0.8}{Ip} * 100$

$20 = \frac {80}{Ip}$

Cross-multiplying, we have;

$20Ip = 80$

$Ip = \frac {80}{20}$

Input power, Ip = 4 Watts

8 0

3 years ago