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3 years ago

The transfer of heat by the movement of a fluid is called

Physics

1 answer:

ikadub [295]3 years ago

8 0

Answer:Convection

Explanation:

Convection is the heat transfer procedure by the movement of liquid or gas molecules. It is a combination of diffusion and bulk motion of molecules. Near the surface of the liquid diffusion process dominates while at certain height bulk motion of liquid dominates.

Convection can be

Natural
Forced

Natural : Natural convection occurs due to density differences

Forced: Force convection occurs when we apply external heat source.

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True or False? A negative energy balance occurs when you take in more calories than you need, and a positive energy balance occu

Rudik [331]

False, because if you take too much calories, you are have too much. That means you are in the positive, you have too much energy.

and if you take fewer, you will have less calories, so less energy.

7 0

3 years ago

An engine that has an efficiency of 25% takes in 200 [J] of heat during each cycle. Calculate the amount of work this engine per

BartSMP [9]

Answer:

$W=50J$

Explanation:

The work done $W$ and the energy taken $Q_{in}$ by a heat engine are related to the efficiency $\eta$ by the expression

$\eta=\frac{W}{Q_{in}}$

The efficiency is $\eta$ =25%, the numerical form of this percentage is 0.25 and the energy taken is $Q_{in}$ =200J. Replacing in the formula:

$0.25=\frac{W}{200}\\W=200*0.25\\W=50J$

5 0

3 years ago

Lewis structure for BeCI2<br>

ludmilkaskok [199]

Answer:

you can see it in the picture

5 0

2 years ago

Standing on the roof of a (42.0+A) m tall building, you throw a ball straight up with an initial speed of (14.5+B) m/s. If the b

RSB [31]

First, we must find the vertical distance traveled upwards by the ball due to the throw. For this, we will use the formula:

2as = v² - u²

Because the final velocity v is 0 in such cases

s = -u²/2a; because both u and a are downwards, the negative sign cancels

s = 14.5² / 2*9.81
s = 10.72 meters

Next, to find the time taken to reach the ground, we need the height above the ground. This is:
45 + 10.72 = 55.72 m

We will use the formula
s = ut + 0.5at²

to find the time taken with the initial velocity u = 0.

55.72 = 0.5 * 9.81 * t²

t = 3.37 seconds

4 0

3 years ago

6 A test of a driver's perception/reaction time is being conducted on a special testing track with level, wet pavement and a dri

mylen [45]

Answer:

a. 10.5 s b. 6.6 s

Explanation:

a. The driver's perception/reaction time before drinking.

To find the driver's perception time before drinking, we first find his deceleration from

v² = u² + 2as where u = initial speed of driver = 50 mi/h = 50 × 1609 m/3600 s = 22.35 m/s, v = final speed of driver = 0 m/s (since he stops), a = deceleration of driver and s = distance moved by driver = 385 ft = 385 × 0.3048 m = 117.35 m

So, a = v² - u²/2s

substituting the values of the variables into the equation, we have

a = v² - u²/2s

a = (0 m/s)² - (22.35 m/s)²/2(117.35 m)

a = - 499.52 m²/s²/234.7 m

a = -2.13 m/s²

Using a = (v - u)/t where u = initial speed of driver = 50 mi/h = 50 × 1609 m/3600 s = 22.35 m/s, v = final speed of driver = 0 m/s (since he stops), a = deceleration of driver = -2.13 m/s² and t = reaction time

So, t = (v - u)/a

Substituting the values of the variables into the equation, we have

t = (0 m/s - 22.35 m/s)/-2.13 m/s²

t = - 22.35 m/s/-2.13 m/s²

t = 10.5 s

b. The driver's perception/reaction time after drinking.

To find the driver's perception time after drinking, we first find his deceleration from

v² = u² + 2as where u = initial speed of driver = 50 mi/h = 50 × 1609 m/3600 s = 22.35 m/s, v = final speed of driver = 30 mi/h = 30 × 1609 m/3600 s = 13.41 m/s, a = deceleration of driver and s = distance moved by driver = 385 ft = 385 × 0.3048 m = 117.35 m

So, a = v² - u²/2s

substituting the values of the variables into the equation, we have

a = v² - u²/2s

a = (13.41 m/s)² - (22.35 m/s)²/2(117.35 m)

a = 179.83 m²/s² - 499.52 m²/s²/234.7 m

a = -319.69 m²/s² ÷ 234.7 m

a = -1.36 m/s²

Using a = (v - u)/t where u = initial speed of driver = 50 mi/h = 50 × 1609 m/3600 s = 22.35 m/s, v = final speed of driver = 30 mi/h = 30 × 1609 m/3600 s = 13.41 m/s, a = deceleration of driver = -1.36 m/s² and t = reaction time

So, t = (v - u)/a

Substituting the values of the variables into the equation, we have

t = (13.41 m/s - 22.35 m/s)/-1.36 m/s²

t = - 8.94 m/s/-1.36 m/s²

t = 6.6 s

4 0

3 years ago