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Ganezh [65]
3 years ago
13

A hair dryer is basically a duct of constant diameter in which a few layers of electric resistors are placed. A small fan pulls

the air in and forces it through the resistors where it is heated. If the density of air is 1.20 kg/m3 at the inlet and 1.015 kg/m3 at the exit, determine the percent increase in the velocity of air as it flows through the dryer
Physics
1 answer:
Mars2501 [29]3 years ago
5 0

Answer:

Therefore % increase in velocity is 18.23 %

Explanation:

we use the equality of mass flow rate and the areas

m_1 = m_2\\p_1v_1 = p_2v_2\\p_1A_1v_1 = p_2A_2v_2\\v_2 = \frac{p_1}{p_2} v_1

The percentage increase in velocity is

Δ v% = \frac{v_2 - v_1}{v_1} \\100%

= \frac{p_1}{p_2} v_1 - v_1.100%

= \frac{\frac{1.2}{1.015} - 1}{1} . 100%

= Therefore % increase in velocity is 18.23 %

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Suppose you throw a rock off a cliff on Earth with an initial horizontal velocity of 3 m/s. Assuming minimal drag and no wind, t
Salsk061 [2.6K]

The horizontal velocity D. remains constant throughout the fall.

Explanation:

The motion of the rock off the cliff is a projectile motion, which consists of two independent motions:

  • A horizontal uniform motion. Since there are no forces acting along the horizontal direction (we consider the air drag to be negligible), the acceleration along this direction is zero, so the horizontal component of the velocity is constant
  • An accelerated motion with constant acceleration. There is one force acting along the vertical direction, the force of gravity, which is constant so the rock experiences a constant acceleration (downward) of magnitude g=9.8 m/s^2 (acceleration of gravity). This means that the vertical component of the velocity keeps changing.

Here in this problem, we are only interested in the horizontal velocity. We said that the horizontal acceleration of the rock is zero: therefore, the horizontal velocity of the rock remains constant during the fall. (if the air drag was not negligible, then it would affect the horizontal velocity, which would decrease as the rock falls).

Learn more about projectile motion:

brainly.com/question/8751410

#LearnwithBrainly

7 0
3 years ago
Read 2 more answers
(c) It is suggested that one side of the copper sheet cools to a lower temperature than the
castortr0y [4]

Answer:

Explanation:

The word "sheet" implies that the copper is quite thin.

Copper is also a very good conductor of heat.

Therefore, with a very short heat flow distance to cover and a high rate of heat transmission, temperature differences on either side of the sheet are almost instantaneously eliminated by heat flow.

3 0
2 years ago
Calculate the average speed in metres per second from Glasgow to Edinburgh
mariarad [96]
This is the same question as the one previously but with more details, so I will just use my previous answer.

1800 to 1820 is 20 minutes.1830 to 1838 is 8 minutes.1840 to 1905 is 25 minutes.
The total time travelled is 20+8+25 = 53 minutes = 3180 seconds.
The distance between Glasgow and Edinburgh is 28 + 12 + 34 = 74 km = 74000 m.

So, the average speed is 74000m/3180s = 23.27 m/s (4 s.f.)
5 0
3 years ago
How many milliliters of water at 25.0°C with a density of 0.997 g/mL must be mixed with 162 mL of coffee at 94.6°C so that the r
Andre45 [30]

Answer:

The volume of water is 139 mL.

Explanation:

Due to the Law of conservation of energy, the heat lost by coffee is equal to the heat gained by the water, that is, the sum of heats is equal to zero.

Q_{coffee} + Q_{water} = 0\\Q_{coffee} = - Q_{water}

The heat (Q) can be calculated using the following expression:

Q=c \times m \times \Delta T

where,

c is the specific heat of each substance

m is the mass of each substance

ΔT is the difference in temperature for each substance

The mass of coffee is:

162mL.\frac{0.997g}{mL} = 162g

Then,

Q_{coffee} = - Q_{water}\\c_{c} \times m_{c} \times \Delta T_{c} = -c_{w} \times m_{w} \times \Delta T_{w}\\m_{c} \times \Delta T_{c} = -m_{w} \times \Delta T_{w}\\m_{w} = \frac{m_{c} \times \Delta T_{c}}{-\Delta T_{w}} \\m_{w}=\frac{162g \times (62.5 \°C - 94.6 \°C ) }{-(62.5 \°C - 25.0 \°C)} \\m_{w} = 139 g

The volume of water is:

139g.\frac{1mL}{0.997g} =139mL

7 0
4 years ago
As a photon from the Sun's core interacts with an atom or ion, the photon gives up its energy to the particle. But the excited p
Natalka [10]

Answer:

Radiative transport

Explanation:

Radiative transportation takes place extensively in the core of the sun. It produces solar energy which are emitted outward from the core of the sun, and it comprises more than 70% of the sun's heat energy. At the core of the sun, the process of nuclear fusion takes where the hydrogen atoms combines with one another, and forms helium, and during this process, it releases a large amount of energy. The photons continuously interacts with the ions (or atoms) and releases this energy to the particles and the excited particles converts the excess amount of energy into another photon which are carried outward by the process of radiative transport.

8 0
4 years ago
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