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3 years ago

What is the formula for convection?

1 answer:

8 0

Convection is transfer of heat between a solid and a moving fluid. Boiling or condensing processes are example for convection processes.

The formula for convection is:

q = hc A dT

where

hc is convective heat transfer coefficient of the process (W/(m2K) or W/(m2oC q
A is the heat transfer area of the surface (m2, ft2)
hc = convective heat transfer coefficient of the process (W/(m2K) or W/(m2oC), Btu/(ft2 h oF))q is heat transferred per unit time (W, Btu/hr)dT is the temperature difference between the surface and the bulk fluid (K or oC, F)

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Net force of 200 newtons is applied to a wagon for 3 seconds

AveGali [126]

Momentum of the wagon increases by (200 x 3)

= 600 newton-sec

= 600 kg-m/sec

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4 years ago

Three students are having a conversation. It goes like this. Allison says: "This problem says, can you add a resistor to the cir

notsponge [240]

Answer:

Nima and Natasha are absolutely correct.

Explanation:

When connecting two resistors in series, their resistances add:

$R_{eq}=R_{1}+R_{2}$

which means that whenever we add a resistance in series, their magnitudes will add, giving us a resistance that is greater than the original resistance, which will demand less current from the battery because of ohm's law:

$I=\frac{V}{R}$

So, the greater the resistance, the smaller the current.

When connecting two resistors in parallel, the reciprocal of ther resistances add:

$\frac{1}{R_{eq}}=\frac{1}{R_{1}}+\frac{1}{R_{2}}$

$R_{eq}=\frac{R_{1}R_{2}}{R_{1}+R_{2}}$

The equivalent resistance will always be less than the smallest resistor in the circuit, so the equivalent resistance will always decrease as more resistors are added. A decrease in the resistance means that the current will increase.

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3 years ago

4. Explain the doppler effect. Be sure to talk about how the wave changes, the perceived change hear by a person that an emitted

Lemur [1.5K]

Answer:

4) The Doppler effect is the frequency change that occurs in a wave by the relative movement of the emitter and the observer

5) Sound originates from a repetitive movement of air molecules

6) The principle of stable superposition that if the medium complies with the elastic regime, the waves traveling in it can be added

Explanation:

4) The Doppler effect is the frequency change that occurs in a wave by the relative movement of the emitter and the observer. In the specific case of the fixed observer, each wave that is emitted travels at a constant speed, but as the emitter approaches the next wave lLa in less time, so the wave maxima are closer to each other

v = λ’ f’

λ‘=λ -Δλ = λ - vs / f

f’= v / λ’ = v / (λ - vs / f) = v / (v / f - vs / f)

f ‘= f v / (v-vs)

5) Sound originates from a repetitive movement of air molecules, this movement creates a longitudinal wave, which we call sound. It is characterized by the air volume module and its density

6) The principle of stable superposition that if the medium complies with the elastic regime, the waves traveling in it can be added

y total = y₁ + y₂

Let's see as an example two waves of the same amplitude that travel in the same direction, if this wave the maximums coincide they add up obtaining that the maximums are twice the amplitude

If the wave goes in the most directive but the maximum of one coincides with the minimum in the other, the sum gives zero,

The wave travels in the opposite direction, in this case the resulting wave in constant in time and we call it resonance

7 0

3 years ago

A ___ is awarded to the opposing team when that team violently or dangerously charges a opponent. ( in soccer)

Helen [10]

Answer:

(C)Direct kick

Explanation:

In a game of soccer (foot-ball) there are lots of rules involved in the game and there is penalty for each of the rules violated. Some of the rules include penalty kick, free kick, throw in, goal kick etc.

Free kick is of two types; direct kick and indirect kick.

Direct kick is awarded when a player outside 18 yards box violently or dangerously charges a opponent.

Indirect kick can be awarded when a goalkeeper inside 18 yards box commits certain offenses.

Therefore, the correction option is (C)Direct kick

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3 years ago

Water flows over a section of Niagara Falls at the rate of 1.2×106 kg/s and falls 50.0 m. How much power is generated by the fal

quester [9]

Answer:

5.88×10⁸ W

Explanation:

Power = energy / time

P = mgh / t

P = (m/t) gh

P = (1.2×10⁶ kg/s) (9.8 m/s²) (50.0 m)

P = 5.88×10⁸ W

7 0

3 years ago