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3 years ago

A person of weight mg, is standing on a scale in an elevator. What will the

Physics

1 answer:

sergejj [24]3 years ago

8 0

Answer:

B. less than mg

Explanation:

A person's weight changes as he rides an elevator at a constant velocity. If the elevator is moving downward, the person's weight becomes lesser. He is considered to be in "free fall" due to gravity. However, the opposite happens when the elevator goes upward. The person will feel heavier because he is going against gravity. This means his weight is more than his actual weight. If the person will stand on an elevator that doesn't move, his weight will just be the same. All of these is due to Newton's Second Law of Motion where an object's acceleration relies on its force and mass.

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Saturn has an orbital period of 29.46 years. In two or more complete sentences, explain how to calculate the average distance fr

vivado [14]

This question can be solved from the Kepler's law of planetary motion.

As per this law the square of time period of a planet is proportional to the cube of semi major axis.

Mathematically it can be written as $T^{2} \alpha R^{3}$

⇒ $T^{2} = KR^{3}$

Here K is the proportionality constant.

If $T_{1}$ and $T_{2}$ are the orbital periods of the planets and

$R_{1}$ and $R_{2}$ are the distance of the planets from the sun, then Kepler's law can be written as-

$\frac{T_{1} ^{2} }{T_{2} ^{2} } =\frac{R_{1} ^{3} }{R_{2} ^{2} }$

⇒ $R_{1} ^{3} =R_{2} ^{3} *\frac{T_{1} ^{2} }{T_{2} ^{2} }$

Here we are asked to calculate the the distance of Saturn from sun.It can solved by comparing it with earth.

Let the distance from sun and orbital period of Saturn is denoted as $R_{1}$ and $T_{1}$ respectively.

Let the distance from sun and orbital period of earth is denoted as $R_{2}$ and $T_{2}$ respectively.

we are given that $T_{1} =29.46 years$

we know that $R_{2} =$ 1 AU and $T_{2} =$ 1 year.

1 AU is the mean distance of earth from the sun which is equal to 150 million kilometre.

Hence distance of Saturn from sun is calculated as -

From Kepler's law as mentioned above-

$R_{1} ^{3} =R_{2} ^{3} *\frac{T_{1} ^{2} }{T_{2} ^{2} }$

= $[1 ]^{3} *\frac{[29.46]^{2} }{[1]^{2} } AU$

$=867.8916 AU^{3}$

⇒ $R_{1} =\sqrt[3]{867.8916}$

=9.5386 AU [ans]

5 0

3 years ago

A student solving a physics problem to find the unknown has applied physics principles and obtained the expression: μkmgcosθ=mgs

BaLLatris [955]

Answer:

$\mu_k=\dfrac{gsin\theta -a}{gcos\theta}$

Explanation:

g = Acceleration due to gravity = 9.80 m/s²

a = Acceleration= 3.6 m/s²

$\theta$ = Angle = 27°

The equation is

$\mu_kmgcos\theta=mgsin\theta -ma$

Mass gets cancelled

$\\\Rightarrow \mu_kgcos\theta=gsin\theta -a$

Rearranging for $\mu_k$

$\\\Rightarrow \mu_k=\dfrac{gsin\theta -a}{gcos\theta}$

The simplified expression is

$\mathbf{\mu_k=\dfrac{gsin\theta -a}{gcos\theta}}$

*the options are incomplete. The above answer is the required solution

4 0

3 years ago

Recoil is noticeable if you throw a heavy ball while standing on roller skates. If instead you go through the motions of throwin

DedPeter [7]

Answer:

Since there is no external force, there is no change (movement) in the center of mass. Internally, the center of mass might change position, but the external result is still zero net velocity.

The net recoil velocity must be zero.

8 0

3 years ago

How does height affects the potential energy of a body?

ivann1987 [24]

Answer:

The higher the height above the more PE (Potential Energy), the body posses as seen in the formula PE = mass*gravity*height. m and g are constant hence only h affect PE

Explanation:

Potential Energy (PE) is the energy the body posses by virtue of its vertical height above the ground because, once the body is released, it will release or create some energy eg hydroelectricity power generation or a car going downhill does not need to be accelerated by the driver since it can roll over on its own due to PE

3 0

3 years ago

Can any one Explain how energy is conserved in a heat pump.

MakcuM [25]

A heat pump draws heat from a cold object and rejects it to a hot one but it requires electrical energy to achieve this. Therefore, electrical energy is converted into heat energy or work in the pump's compressor. Therefore, energy is conserved.

3 0

4 years ago