Answer:
During convection, hot material expands & rises then moves to the side and cools & sinks. this circular pattern is called a convection current.
Explanation:
Convection is one of the three methods of transfer of heat. It occurs only in fluids (liquids or gases).
Convection occurs when there is a source of heat that heats a fluid, such as in a boiling pot of water. The water which is on the bottom of the pot becomes warmer before than the water at the top (because it is closer to the flame), and so it becomes less dense: for this reason, it expands and it becomes rising. On the contrary, the water on top is colder, so it is more dense and starts sinking, replacing the warmer water. As the new part of water gets warmer, it starts rising, and so the process is continuously repeated. This circular current is called convection current.
Answer:
R₁ = 50.77 Ω
Explanation:
Since, we know that:
Electric Power = P = VI
but from Ohm's Law:
V = IR
(or) I = V/R
Therefore,
P = V²/R
(OR) R = V²/P
where,
V = Battery Voltage
R = Resistance of combination
FOR SERIES COMBINATION:
R = Rs = (57 V)²/48 W
Rs = 67.69 Ω
but, we know that:
Rs = R₁ + R₂
R₁ + R₂ = 67.69 Ω
R₁ = 67.69 Ω - R₂ __________ eqn (1)
FOR PARALLEL COMBINATION:
R = Rp = (57 V)²/256 W
Rp = 12.69 Ω
but, we know that:
Rp = (R₁R₂)/(R₁ + R₂) = 12.69 Ω
using eqn (1) and value of R₁ + R₂, we get
Rp = 12.69 = R₂(67.69 - R₂)/67.69
859.08 = 67.69 R₂ - R₂²
R₂² - 67.69 R₂ + 859.08 = 0
Solving this quadratic equation we get the answers:
Either, R₂ = 50.76 Ω
Either, R₂ = 16.92 Ω
Since, it is stated in the question that R₁ > R₂. Therefore, we choose the second value. So,
<u>R₂ = 16.92 Ω</u>
using this value in eqn (1), we get:
R₁ = 67.69 Ω - 16.92 Ω
<u>R₁ = 50.77 Ω</u>
Answer:
B. The escape speed of the Moon is less than that of the Earth; therefore, less energy is required to leave the Moon.
Explanation:
Since the speed required to escape from the gravitational attraction of the Moon is less than the speed required to escape from the gravitational attraction of the Earth, less energy is required to travel from the Moon to the Earth, than is required to travel from the Earth to the Moon. This is because the kinetic energy is directly proportional to the square of the velocity.
If the heart is beating at 76. 0 beats per minute, the Frequency of heart's oscillations in hertz is 1.25 Hertz.
The Frequency is defined as the number of oscillations completed in 1s.
Our heart beats continuously giving rise to the frequency of the heart.
Measuring frequency would be possible if we measure the time in seconds.
75 beats per minute means that 75 beats occur in 60s.
Frequency = Number of beats / Total time taken
Frequency = 75 / 60
Frequency = 1.25 Hz
Hence, number of beats per second is 1.25 Beats.
Beats per second or Cycles per second is same as the frequency of oscillation called as Hertz (Hz)
Hence, frequency of the heart oscillation is 1.25 Hertz (Hz).
Learn more about Frequency here, brainly.com/question/14316711
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I think it’s the third one idk tho
