Tag: weightlessness

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

An astronaut,inside an earth`s satellite experiences weightlessness because

  1. he is falling freely

  2. no external force is acting on it

  3. no reaction is exerted by the floor of the satellite

  4. he is far away from the earth`s surface
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An astronaut,inside an earth`s satellite experiences weightlessness because he is falling freely.

so that the correct option is A.

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

Statement -1 :- A person feels weightlessness in an artificial satellite of the Earth. However a person on the Moon (natural satellite) feels his weight.
 and
 Statement - 2 :- Artificial satellite is a freely falling body and on the Moon surface, the weight is mainly due to Moon's gravitational attraction.

  1. Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for statement-1

  2. Statement-1 is True, Statement-2 is True; Statement-2 is not a correct explanation for statement-1

  3. Statement-1 is true, Statement -2 is False

  4. Statement-1 is true, Statement -2 is True
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Both statements are true. An artificial satellite is in free fall, leading to weightlessness. On the Moon, you are standing on a surface, so the normal force balances the gravitational pull, meaning you feel weight. Statement 2 is a true statement, but it doesn't explain the reason for the difference in the sensation of weightlessness (which is about the presence of a normal force, not just the source of gravity).

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

While orbiting around the earth in a apaceship, an astronaut experiences

  1. more weight

  2. lesser weight

  3. weightlessness

  4. nothing at all
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • When an astronaut is orbiting the earth, he is in a state of free fall along with the space vehicle, hence the astronaut is not able to exert his mass on its surface. This condition is called weightlessness condition.
  • Hence,option C is correct.


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

    Motion of artificial satellite around the earth is powered by :

    1. Liquid fuel

    2. Solar energy

    3. Atomic energy

    4. None of these
    Reveal answer Fill a bubble to check yourself
    D Correct answer
    Explanation

    Answer is D.

    The orbit of an artificial earth satellite is an ellipse whose focus is at the center of the earth (in a particular case, a circle) and which maintains an unchanged position in space. Movement along such an orbit is called undisturbed motion and proceeds on the assumption that the earth attracts, according to Newtons law, like a sphere with spherical density distribution and that the satellite is affected only by the earths gravitational attraction.
    Such factors as atmospheric drag, compression of the earth, solar radiation pressure, and the attraction of the moon and sun are the reasons for deviations from undisturbed motion. Because of atmospheric drag, satellites in orbits at altitudes of several hundred kilometers gradually descend and, entering the dense layers of the atmosphere at an altitude of 120130 km and lower, disintegrate and burn up; thus, they exist for a limited period.
    Hence, the m    otion of artificial satellite around the earth is NOT powered by any of the options given.

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

    While orbiting around the earth in a spaceship, an astronaut weight becomes

    1. greater than their real weight

    2. lesser than their real weight

    3. zero

    4. infinity
    Reveal answer Fill a bubble to check yourself
    C Correct answer
    Explanation

    In a spaceship the astronaut weighs zero. Since there is no gravity in the space person feels weightless. Apart from these space is a vacuum and there is no air resistance and thus we feel weightless.

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

    Weightlessness in a satellite is experienced because 

    1. of inertia

    2. the gravitational force acting on the satellite is zero

    3. of centre of gravity

    4. centrifugal acceleration negates the acceleration due to gravity
    Reveal answer Fill a bubble to check yourself
    D Correct answer
    Explanation

    The satellite rotates in a circular path or elliptical path such that gravitational pull is always balanced by centrifugal force due to the rotational motion of satellite.

    Thus a body in the satellite will feel weightlessness.
    although force of gravity on a body is never zero but it is balanced by centrifugal force in  this case.
    so option D is correct.

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

    A satellite is orbiting the earth at 17,500 MPH, a rock is released from the satellite. Identify what would happen to the rock.

    1. The rock would orbit the earth at a velocity of 17,500 MPH next to the satellite

    2. As the rock cannot generate its own force, it will slow down

    3. Gravity will pull the rock towards earth

    4. As the rock is smaller than the satellite, it will accelerate and orbit at a greater velocity

    5. As the rock is smaller than the satellite, its inertia will pull it further away from earth
    Reveal answer Fill a bubble to check yourself
    A Correct answer
    Explanation

    The satellite moves in the orbit with a constant speed in circular path, with centripetal acceleration being provided by the force of gravity on it.

    The radius of orbit can be found by 
    $\dfrac{GMm}{R^2}=\dfrac{mv^2}{R}$
    $\implies R=\dfrac{GM}{v^2}$ which is independent of the mass of projectile(satellite)
    When the stone is released from the orbiting satellite, it moves with the same speed. Its mass is much lesser than that of satellite, but the orbital radius is independent of its mass, depending only upon the speed which is same. Thus is would also orbit the earth with same speed in same orbit as that of satellite.

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

    A man weighs $75 kg$ on the surface of the earth. His weight in a geostationary satellite is:

    1. infinity
    2. $150 kg$

    3. zero
    4. $75/2 kg$
    Reveal answer Fill a bubble to check yourself
    C Correct answer
    Explanation

    A geostationary satellite revolves around the earths with the same time period of earth's rotation, that is 24 hours.
    Since it revolves with same speed, the relative velocity is zero with respect to earth and hence any body inside a geostationary satellite doesn't feel the gravity.
    So, the weight would be equal to zero.

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

    A pendulum beats seconds on the earth. Its time period on a stationary satellite of the earth will be

    1. Zero
    2. $1\ s$
    3. $2\ s$

    4. Infinity
    Reveal answer Fill a bubble to check yourself
    D Correct answer
    Explanation

    Inside a satellite, every object experiences weightlessness

    Therefore Time period of a pendulum inside a satellite is $T= 2\pi \sqrt{\cfrac{L}{g}}$
    as $g=0$
    $\therefore T=\infty$ (Infinity)
    A pendulum beats seconds on the earth. Its time period on a stationary satellite of the earth will be Infinity.