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2 years ago

Why a drop of spirit on the hand feels colder than a drop of water at the same temperature

Physics

1 answer:

brilliants [131]2 years ago

5 0

Answer:

This is because spirit has a lower boiling point when compared to water

Explanation:

spirit has a lower boiling point when compared to water which means it has the capacity to pull more heat from your hand and also it can do this very fast. This is why our hand feels colder.

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A force of 960 newtons stretches a spring 4 meters. A mass of 60 kilograms is attached to the end of the spring and is initially

Drupady [299]

Answer:

x(t) = - 6 cos 2t

Explanation:

Force of spring = - kx

k= spring constant

x= distance traveled by compressing

But force = mass × acceleration

==> Force = m × d²x/dt²

===> md²x/dt² = -kx

==> md²x/dt² + kx=0 ------------------------(1)

Now Again, by Hook's law

Force = -kx

==> 960=-k × 400

==> -k =960 /4 =240 N/m

ignoring -ve sign k= 240 N/m

Put given data in eq (1)

We get

60d²x/dt² + 240x=0

==> d²x/dt² + 4x=0

General solution for this differential eq is;

x(t) = A cos 2t + B sin 2t ------------------------(2)

Now initially

position of mass spring

at time = 0 sec

x (0) = 0 m

initial velocity v= = dx/dt= 6m/s

from (2) we have;

dx/dt= -2Asin 2t +2B cost 2t = v(t) --- (3)

put t =0 and dx/dt = v(0) = -6 we get;

-2A sin 2(0)+2Bcos(0) =-6

==> 2B = -6

B= -3

Putting B = 3 in eq (2) and ignoring first term (because it is not possible to find value of A with given initial conditions) - we get

x(t) = - 6 cos 2t

==>

4 0

3 years ago

Select all that apply to electrons and energy levels. - Scientists have not yet determined exactly why electrons do not collapse

Elenna [48]

Answer:

- The limitation of the maximum number of electrons in a given energy level can be used to account for the periodic recurrence of properties as the number of electrons increases.

Explanation:

First - Scientists have not yet determined exactly why electrons do not collapse into the nucleus. FALSE: Scientists do know why electrons do not collapse. Since the beginins of quantum mechanics it's known that the energy at small scales is quantized, that means there only can be certain values meaning that the energy do not change continously. In the case of the electron, it can only have certain levels of energy, that means they do not radiate continously as the go arround the atom, instead it is only allowed to have a certain amount of energy in a given state therefore it can not lose energy continously collapsing into the nucleus.

Second - Electrons cannot be located between levels except when they are in the process of moving. FALSE: We can not say that a electron moves between energy levels, it only can exist in any of the levels, but never in between. Also, the electron in any of its possible energy lavels can not be located with complete certainty due to the uncertainty principle.

Fourth - Electrons have any random energy. FALSE: as exposed above the electrons can only have certain cuantized energy levels acordinly to the rules of quantum physics

Fifth - Electrons can be found between energy levels. FALSE: Like said before we can not say that a electron exists between energy levels, it only can exist in any of the allowed levels, but never in between.

Thirth (correct one) : - The limitation of the maximum number of electrons in a given energy level can be used to account for the periodic recurrence of properties as the number of electrons increases. TRUE: the maximum number of electrons allowed in a given energy level directly determines the tipe of bond an atom can made with another (this due to the number of electrons in the higest energy level), so for example the elements in the left of a given row of the periodic table tend to have ionic bonds, but in the other hand the elements on right side tend form more covalent bonds. And this characteristic directly correllate with diferent properties of the elements.

7 0

3 years ago

A beaker of vegetable oil contains a beam of light that is aimed at a surface at an angle of 34 degrees as shown. If the index o

OverLord2011 [107]

Answer:

Angle of reflection of light is 34 degree

Explanation:

As per law of reflection of light we know that

angle of incidence of light = angle of reflection of light

So here we know that

angle of incidence on the surface of oil is given as

$\theta_i = 34 degree$

so we know that

$\theta_i = \theta_r$

so here we can say that reflection angle of light will be same as angle of incidence

$\theta_r = 34 degree$

8 0

3 years ago

A 150 kg line backer sacks the 120 kg quarterback. With what force is the quarterback sacked if the line backer has an accelerat

Gekata [30.6K]

Answer:

The force required to move the quarterback with linebacker is <u>1215 N</u>

Explanation:

$\text { Mass of linebacker } \mathrm{m}_{2}=150 \mathrm{kg}$

$\text { Mass of quarterback } \mathrm{m}_{2}=120 \mathrm{kg}$

$\text { Moved at an acceleration }(a)=4.5 \mathrm{m} / \mathrm{s}^{2}$

Using Newton's second law, it is established that F = Ma

Where F is net force acting on the system, a is the acceleration and M is mass of the two object $\left(m_{1}+m_{2}\right)$

Now consider both $\mathrm{m}_{1} \text { and } \mathrm{m}_{2}$ as a system, so net force acting on the system is $\text { Force }=\left(m_{1}+m_{2}\right) a$

Substitute the given values in the above formula,

$\text { Force }=(150+120) \mathrm{kg} \times 4.5 \mathrm{m} / \mathrm{s}^{2}$

$\text { Force }=270 \mathrm{kg} \times 4.5 \mathrm{m} / \mathrm{s}^{2}$

Force = 1215 N

<u>1215 N </u>is the force required to move the quarterback with linebacker.

5 0

3 years ago

A Red-Tailed Hawk leaves its nest and flies 100.0 meters across the sky in 20 seconds, when it spots a garter snake on the groun

igomit [66]

Speed = distance / time.

Speed of him leaving the nest:
S = 100 / 20sec

5 m/s.

Catching the snake:
S2 = 50 / 5sec

10 m/s.

Average of 5& 10 = 7.5

7.5 m/s has to be the answer.

3 0

2 years ago

Why a drop of spirit on the hand feels colder than a drop of water at the same temperature​

Why a drop of spirit on the hand feels colder than a drop of water at the same temperature