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4 years ago

How does air blowing from a fan make you feel cooler if the air is the same temperature?

1 answer:

8 0

Air moving across your skin promotes evaporation of the moisture on
your skin, and evaporation always carries heat energy away with it.

That's the whole purpose of sweating ... Your insides say to each other:
"We're burning up in here and we've got to get some relief ! Pump that
moisture out to the skin where it can evaporate and carry away some of
this heat energy that's building up in here!"

That's why you feel even hotter on a very humid day ... because you're
not able to evaporate as much moisture into air that's already very humid,
even if it's moving.

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Problem: The frequency of an FM radio station is 89.3 MHz. Calculate its period. Part B: From the Library, select the general eq

vekshin1

Answer:

Time period, $T=1.11\times 10^{-8}\ s$

Explanation:

We have,

The frequency of an FM radio station is 89.3 MHz.

It is required to find the period of the wave.

The reciprocal of frequency is called time period of a wave. It can be given by :

$T=\dfrac{1}{f}\\\\T=\dfrac{1}{89.3\times 10^{6}\ Hz}\\\\T=1.11\times 10^{-8}\ s$

So, the period of the wave is $1.11\times 10^{-8}\ s$ .

5 0

3 years ago

An aluminum "12 gauge" wire has a diameter d of 0.205 centimeters. The resistivity ρ of aluminum is 2.75×10−8 ohm-meters. The el

Alborosie

Answer:

I = 4.75 A

Explanation:

To find the current in the wire you use the following relation:

$J=\frac{E}{\rho}$ (1)

E: electric field E(t)=0.0004t2−0.0001t+0.0004

ρ: resistivity of the material = 2.75×10−8 ohm-meters

J: current density

The current density is also given by:

$J=\frac{I}{A}$ (2)

I: current

A: cross area of the wire = π(d/2)^2

d: diameter of the wire = 0.205 cm = 0.00205 m

You replace the equation (2) into the equation (1), and you solve for the current I:

$\frac{I}{A}=\frac{E(t)}{\rho}\\\\I(t)=\frac{AE(t)}{\rho}$

Next, you replace for all variables:

$I(t)=\frac{\pi (d/2)^2E(t)}{\rho}\\\\I(t)=\frac{\pi(0.00205m/2)^2(0.0004t^2-0.0001t+0.0004)}{2.75*10^{-8}\Omega.m}\\\\I(t)=4.75A$

hence, the current in the wire is 4.75A

4 0

3 years ago

When a car is traveling 120 km/h how many times more kinetic energy would it have than if it were

LekaFEV [45]

Answer: 9

Explanation:

Kinetic energy is the energy possessed by a moving object. It is measured in joules, and depends on the mass (m) of the object and the speed (v) by which it moves i.e K.E = 1/2 x mass x velocity^2

So, car is traveling 120 km/h

KE = 1/2x m x (120 km/h)^2

KE = 0.5 x m x 14400

KE1 = 7200m

So, car is traveling 40 km/h

KE = 1/2x m x (40 km/h)^2

KE = 0.5 x m x 1600

KE2 = 800m

Now, divide the value of kinetic energy obtained during 120 km/h by that obtained during 40 km/h

i.e 7200m / 800m

= 9

Thus, the kinetic energy will be 9 times more at a speed of 120 km/h than at 40 km/h

4 0

3 years ago

a radio controlled car rolls 10 m south then reverses direction and rolls 8 m north the car traveled a distance of 18 m and has

EastWind [94]

The displacement is 2 m south

Explanation:

Distance and displacement are two different quantities:

Distance is the total length of the path covered by an object during its motion, regardless of the direction. It is a scalar quantity
Displacement is a vector connecting the initial position to the final position of motion of an object. The magnitude of the displacement is the distance in a straight line between the two points

For the car in this problem, the motion is:

10 m south

8 m north

Taking north as positive direction, we can describe the two parts of the motion as

$d_1 = -10 m$

$d_2 = +8$ m

Therefore, the final position of the car with respect to the original position is

$x_f = -10 + 8 = -2 m$

which means 2 m south: so, the displacement of the car is 2 m south.

Learn more about distance and displacement:

brainly.com/question/3969582

#LearnwithBrainly

5 0

3 years ago

By 1949 Americans who lived within the range of a television stations in the country could watch TV, vastly changing the way tha

fredd [130]

Answer: Microwaves.

Explanation: First, we have a trivial answer, and that is the visible light, which is responsible to let the information on the tv to be seen by the user.

Now, TV technology was possible thanks to the microwaves, that are used because these can carry more energy than other types, and these microwaves needed a special technology because they couldn't be handled by the current technology at the time.

5 0

4 years ago