Tag: application of newton's law of motion

Questions Related to application of newton's law of motion

Weightlessness experienced while orbiting the earth in a spaceship is the result of

physics gravitation: planets and satellites weightlessness application of newton's law of motion escape velocity

  1. Inertia

  2. Accelaration

  3. Zero gravity

  4. Centre of gravity

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Correct Option: C
Explanation:

Weightlessness means that there is no reaction on a body from the floor. Since both the artificial satellite & the astronaut have same centripetal acceleration (as in a lift; which is falling freely, we does not feel any weight, because both lift & we fall with same acceleration). so the astronaut does not feel any weight inside the space craft

The period of a simple pendulum inside a satellite orbiting earth is

physics gravitation: planets and satellites weightlessness application of newton's law of motion escape velocity

  1. $\displaystyle zero$

  2. $\displaystyle \infty $

  3. can be any integer

  4. cant say

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Correct Option: B
Explanation:

$\displaystyle T=2\pi \sqrt {\frac{l}{g}}$
but inside the satellite $\displaystyle g=0$
So $\displaystyle T=\infty$ 

A body suspended from a spring balance is placed in a satellite. Reading in balance is $W _1$ when the satellite moves in an orbit of radius $R$. Reading in balance is $W _2$ when the satellite moves in an or bit of radius $2R.$ Then.

physics gravitation: planets and satellites weightlessness application of newton's law of motion escape velocity

  1. $W _1 = W _2$

  2. $W _1 > W _2$

  3. $W _1 < W _2$

  4. $W _1 =2 W _2$

Show answer
Correct Option: A
Explanation:

Since,Both the satellites are freely falling bodies.
so,$W _1=W _2$

Moon is a satellite of the Earth, but weightlessness is not experienced at the surface of the Moon because

physics gravitation: planets and satellites weightlessness application of newton's law of motion escape velocity

  1. its distance from the Earth is more.

  2. it is a natural satellite.

  3. its size is big but density is very low.

  4. its own mass is more.

Show answer
Correct Option: D
Explanation:

As Moon has its mass, thus it posses its own gravity ($\frac {1}{6}$th of that of the Earth). Hence, weightlessness is not experienced at the surface of the Moon.

Weightlessness experienced in a spaceship is due to

physics gravitation: planets and satellites weightlessness application of newton's law of motion escape velocity

  1. absence of of inertia.

  2. absence of gravity.

  3. absence of accelerating force.

  4. free fall of the spaceship.

Show answer
Correct Option: D
Explanation:

It is a misconception that there is no gravity in space.
An astronaut experiences weightlessness due the fact that as the spacecraft revolves around the Earth, the astronaut is continuously falling towards the Earth. This is similar to what a person standing in an elevator, that is falling freely, would experience. The person would be weightless as the elevator falls.

Read the assertion and reason carefully to mark the correct option out of the options given below :

Assertion : An astronaut in a satellite feels weightlessness.
Reason : As observed by another astronauts in the same satellite, force of gravity and centrifugal force balance each other.

physics gravitation: planets and satellites weightlessness application of newton's law of motion escape velocity

  1. If both assertion and reason are true and the
    reason is the correct explanation of the assertion

  2. If both assertion and reason are true but reason
    is not the correct explanation of the assertion

  3. If assertion is true but reason is false

  4. If assertion is false but reason is true

Show answer
Correct Option: A
Explanation:

In a satellite, weightlessness is felt.

The weight of a person in a satellite is balanced by the centrifugal force due to orbiting of the satellite around the earth, i.e.,
$mg=\dfrac{mv^2}{r}$

A body is suspended from a spring balance kept in a satellite The reading of the balance is $\displaystyle W _{1}$ when the satellite goes in an orbit of radius $R$ and is $\displaystyle W _{2}$ when it goes in an orbit of radius $2R$ Then

physics gravitation: planets and satellites weightlessness application of newton's law of motion escape velocity

  1. $\displaystyle W _{1}=W _{2}$

  2. $\displaystyle W _{1}< W _{2}$

  3. $\displaystyle W _{1}>W _{2}$

  4. $\displaystyle W _{1}\neq W _{2}$

Show answer
Correct Option: A
Explanation:

Answer is A.

The reading on the spring balance is independent of the radius and thus both weight will be the same. Also, there is no gravitational force acting on a satellite.
 
Hence, ${ W } _{ 1 }={ W } _{ 2 }$.

A 60kg man goes around the earth in a satellite. In the satellite, his weight will be

physics gravitation: planets and satellites weightlessness application of newton's law of motion escape velocity

  1. 60 N

  2. 60 Kg

  3. 600 N

  4. Zero

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Correct Option: D
Explanation:

The gravitational force acting on the man in the satellite will be zero as there is no gravitational pull on man in the space hence his weight will be zero.

Consider a satellite going round the earth in a circular orbit. Which of the following statements is wrong?

physics gravitation: planets and satellites weightlessness application of newton's law of motion escape velocity

  1. It is a freely falling body

  2. It is a moving with constant speed.

  3. It is acted upon by a force directed away from the centre of the earth which counter- balances the gravitational pull.

  4. Its angular momentum remains constant.

Show answer
Correct Option: C
Explanation:

Satellite going around the earth in circular orbit is in state of free fall, and its speed is constant. speed depends upon the radius of orbit of satellite.

So Its angular velocity($\omega=v\times r$) is also constant and thus angular momentum $m\omega$ is also constant.
Apart from gravitational pull of the earth, there is no other force on the satellite. So option C is incorrect.

The International Space Station is currently under construction. Eventually, simulated earth gravity may become a reality on the space station. What would the gravitational field through the central axis be like under these conditions?

physics gravitation: planets and satellites weightlessness application of newton's law of motion escape velocity

  1. Zero

  2. $0.25\ g$

  3. $0.5\ g$

  4. $0.75\ g$

  5. $1\ g$

Show answer
Correct Option: A
Explanation:

Simulated earth gravity can be realized by rotating the space station about a central axis. This rotation creates centrifugal force on the people inside the space station away from the central axis. Thus, $g={ \omega  }^{ 2 }R $ at the central axis $R=0$. So, gravitational field is zero.