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3 years ago

Evaporation of sweat cools the skin because

Physics

1 answer:

Law Incorporation [45]3 years ago

6 0

Answer: c. the molecules with the highest energy evaporate first, lowering the temperature of the sample

Explanation:

The process by which liquid starts to change into vapor phase at any temperature is known as evaporation.

During evaporation , the molecules which possess higher energies escape from the upper layer into vapor phase. the molecules which escape draw energy from surroundings and thus decrease the energy of the surroundings and hence lead to decrease in temperature.

As temperature of the system is directly proportional to the energy of the system , thus decrease in energy leads to decrease in temperature.

$K.E=\frac{3RT}{2}$

K.E. = Kinetic energy

T = temperature

R= gas constant

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A 17.6-kg block rests on a horizontal table and is attached to one end of a massless, horizontal spring. By pulling horizontally

leonid [27]

In order get the block up to a speed of 3.58 m/s in 1.77 s, it must undergo an acceleration a of

a = (3.58 m/s) / (1.77 s) ≈ 2.02 m/s²

When the spring is getting pulled, Newton's second law tells us

• the net vertical force is

∑ F = n - mg = 0

where ∑ F is the net force, n is the magnitude of the normal force, and mg is the weight of the block - it follows that n = mg ; and

• the net horizontal force is

∑ F = F - f = ma

where F is the applied force, f is kinetic friction, m is the block's mass, and a is the acceleration found earlier. F stretches the spring by x = 0.250 m, so we have

F - f = kx - µn = kx - µmg = ma

where k is the spring constant and µ is the coefficient of kinetic friction.

When the block is being pulled at a constant speed, Newton's second law says

• the net vertical force is still

∑ F = n - mg = 0

so that n = mg again; and

• the net horizontal force is

∑ F = F - f = 0

This time, F stretches the spring by y = 0.0544 m, so we have

F - f = ky - µmg = 0

Solve the equations in boldface for k and µ :

kx - µmg = ma

ky - µmg = 0

==> k (x - y) = ma

==> k = ma / (x - y)

==> k = (17.6 kg) (2.02 m/s²) / (0.250 m - 0.0544 m) ≈ 182 N/m

Then

ky - µmg = 0

==> µ = ky / (mg)

==> µ = (182 N/m) (0.0544 m) / ((17.6 kg) g) ≈ 0.0574

3 0

3 years ago

A train travels due south at 25 m/s (relative to the ground) in a rain that is blown toward the south by the wind. The path of e

olasank [31]

Answer:

Explanation:

Given

Train travels towards south with a velocity if $v_t=25\ m/s$

Rain makes an angle of $\theta =66^{o}$ with vertical

If an observer sees the drop fall perfectly vertical i.e. horizontal component of rain velocity is equal to train velocity

suppose $v_r$ is the velocity of rain with respect to ground then

$v_r\sin\theta =v_t$

$v_r\times \sin (66)=25$

$v_r=27.36\ m/s$

Therefore velocity of rain drops is 27.36 m/s

8 0

3 years ago

Is charging by contact the same as charging by conduction?

netineya [11]

Answer:So, the difference between charging by induction and conduction comes down to the contact of the neutral object and the object used to charge it. Conduction requires direct contact, while induction does not.

Explanation:

8 0

3 years ago

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A neutron has

zavuch27 [327]

Answer:

Explanation:

a neutron does not have a positive nor negative charge it remains neutral

6 0

2 years ago

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