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Lina20 [59]
3 years ago
10

You are standing on a scale in an elevator. suddenly you notice your weight decreases. what do you conclude? a. the elevator is

accelerating downwards. b. the elevator is accelerating upwards. c. the elevator is moving at a constant velocity upwards. d. your diet is working. e. the elevator is moving at a constant velocity downwards.
Physics
1 answer:
solong [7]3 years ago
3 0

Answer:

The elevator is accelerating downwards.

Explanation:

When an elevator accelerating downward it moves together with the person inside and the weight of the person does not change, but if the person is standing on a scale the contact force between the person and the scale is reduced.  The scale therefore has to push upward with less force on the person to support the person's weight. Therefore the Normal Force is smaller, so the reading on the scale becomes less than the true weight.

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A ball that has a mechanical energy of 65 J has 12 J of kinetic energy. The ball has J of potential energy.
otez555 [7]
53
i did it and got it right guys i hope it helps a lot
4 0
3 years ago
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8 points)Antireflection coating can be used on the eyeglasses to reduce the reflection of light: a) A 100nm thick coating is app
NemiM [27]

Answer:

- the coating’s index of refraction is 1.25

- the required thickness is 104.1667 nm

Explanation:

Given the data in the question;

Thickness of coating t = 100 nm

wavelength λ = 500nm

we know that refractive index is;

t = λ/4n

make n, the subject of formula

t4n = λ

n = λ / 4t

we substitute

n = 500 / ( 4 × 100 )

n = 500 / 400

n = 1.25

Therefore, the coating’s index of refraction is 1.25

2)

given that;

Index of refraction of the coating; n = 1.20

λ = 500 nm

thickness of coating t = ?

t = λ / 4n

we substitute

t = 500 / ( 4 × 1.2 )

t = 500 / 4.8

t = 104.1667 nm

Therefore, the required thickness is 104.1667 nm

4 0
3 years ago
A cube of water 10 cm on a side is placed in a microwave beam having Ea = 11 kV/m‘ The microwaves illuminate one faceofthe cube,
Shtirlitz [24]

Answer:

The time is 133.5 sec.

Explanation:

Given that,

One side of cube = 10 cm

Intensity of electric field = 11 kV/m

Suppose How long will it take to raise the water temperature by 41°C Assume that the water has no heat loss during this time.

We need to calculate the rate of energy transfer from the beam to the cube

Using formula of rate of energy

P=(0.80)IA

P=0.80\times\dfrac{c\mu_{0}E^2}{2}\times A

Put the value into the formula

P=0.80\times\dfrac{3\times10^{8}\times8.85\times10^{-12}\times(1.1\times10^{4})^2}{2}\times(10\times10^{-2})^2

P=1285.02\ W

We need to calculate the amount of heat

Using formula of heat

E =mc\Delta T

E =\rho Vc\Delta T

Put the value into the formula

E=1000\times(0.10)^3\times4186\times41

E=171626\ J

We need to calculate the time

Using formula of time

t=\dfrac{E}{P}

Put the value into the formula

t=\dfrac{171626}{1285.02}

t=133.5\ sec

Hence, The time is 133.5 sec.

3 0
4 years ago
Nikolas had an idea that he could use the compressed carbon dioxide in a fire extinguisher to propel him on his skateboard.
Vikentia [17]
The Newton’s law Nikolas would use to come up with this idea is the <span>Third law that states:

</span><span>When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
</span>
So, in this case, let's name the first Body A which is the skateboard and the second body B which is <span>the compressed carbon dioxide in a fire extinguisher. Then, as shown in the figure below, according to the Third law:

</span>FA = -FB<span>

</span>

8 0
3 years ago
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two porters are available to carry a long timber wood.out of them one is weak.how to do you make less load to the weak one? writ
marshall27 [118]

Answer:

Please find the answer in the explanation.

Explanation:

Given that two porters are available to carry a long timber wood.out of them one is weak. how do you make less load to the weak one?

We can make the weak one to carry less load through two different ways or means.

First, if we can locate the centre of gravity and centre of mass of the long timbre wood, the week one can carry the other end away from the center of gravity and centre of mass.

Second, the strong porter can carry the long timbre wood almost to the fulcrum and allow the weak one to support at the other end. By doing this, the weak one will only carry light portion of the load.

4 0
3 years ago
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