Self Studies

Gravitation Test - 43

Result Self Studies

Gravitation Test - 43
  • Score

    -

    out of -
  • Rank

    -

    out of -
TIME Taken - -
Self Studies

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Self Studies Self Studies
Weekly Quiz Competition
  • Question 1
    1 / -0
    A Gravitational force between two masses at a distance d' d ' apart is 6 N.6\ N. If these masses are taken to the moon and kept at same separation, then the force between them will be.
    Solution
    Gravitational force between two objects is Gm1m2r2\dfrac{Gm_{1}m_{2}}{r^2}.
    Since at moon, the mass of the objects and the distance between them remain the same, and G is obviously a universal constant, the force between them remains the same.
  • Question 2
    1 / -0
    The acceleration due to gravity on the surface of a planet, which has both mass and radius half of those of the earth is:
    Solution
    Answer is B.

    The formula for the acceleration due to gravity is based on Newton's Second Law of Motion and Newton's Law of Universal Gravitation. These two laws lead to the most useful form of the formula for calculating acceleration due to gravity: g=Gmr2g=\frac { Gm }{ { r }^{ 2 } } , where g is the acceleration due to gravity, G is the universal gravitational constant, M is mass, and R is distance. 
    In this case, both mass and radius is half of those of the earth.
    So, the acceleration due to gravity becomes g=Gm2 (r2 ) 2=2×Gmr2=2×9.8m/s2=19.6m/s2g=\frac { G\frac { m }{ 2 }  }{ { \left( \frac { r }{ 2 }  \right)  }^{ 2 } } =2\times \frac { Gm }{ { r }^{ 2 } } =2\times 9.8\quad m/{ s }^{ 2 }\quad =\quad 19.6\quad m/{ s }^{ 2 }.
    Hence, the acceleration due to gravity is 19.6m/s2{19.6 m/s ^2}.
  • Question 3
    1 / -0
    Two object are placed at some distance, if their masses become two times and distance between them becomes half then value of new gravitational force will be :
    Solution
    Newtons Law of Gravitation states that the force of gravity, FgF_g, between two particles of mass m1m_1 and 
    m2m_2 has a magnitude of
    Fg=Gm1m2d2{ F }_{ g }\quad =\quad \dfrac { G{ m }_{ 1 }{ m }_{ 2 } }{ { d }^{ 2 } }
    where  r is the distance between the center of the two masses and G is the gravitational constant.
    In this case, the masses are doubled and the radius is halved. So the Force becomes 
    Fg=G2m12m2(d2)2=16Gm1m2d2{ F }_{ g }\quad =\quad \dfrac { G{ 2m }_{ 1 }{ 2m }_{ 2 } }{ { \bigg (\dfrac { d }{ 2 } \bigg ) }^{ 2 } } =16\dfrac { G{ m }_{ 1 }{ m }_{ 2 } }{ { d }^{ 2 } } .
    Hence, the new gravitational force will be 16 times more.
  • Question 4
    1 / -0
    A freely falling body:
    Solution
    A freely falling body will experience a downward force equal to mgmg. But when we talk about weight, it is the reaction force acting on the body. The freely falling body does not experience this reaction force and that is why it is weightless.
    Hence the correct answer is option AA.
  • Question 5
    1 / -0
    Two bodies of masses m1{m_1} and m2{m_2}  are placed at distance X from each other. If X is kept constant and the masses of the two bodies are increased to 2m1{2m_1}, and 2m2{2m_2}, then the value of gravitational force between them will become
    Solution

    Answer is C.

    The force of gravitational attraction is directly dependent upon the masses of both objects and inversely proportional to the square of the distance that separates their centres. Newton's conclusion about the magnitude of gravitational forces is summarised symbolically as

    Fm1.m2X2F\propto \dfrac { m_1.m_2 }{ { X }^{ 2 } }

    F=Gm1.m2X2F=G \dfrac { m_1.m_2 }{ { X }^{ 2 } }   Where, G:G: Gravitational constant

    where, m1m_1 and m2m_2 are masses of the object and X is the distance of sepration between them. 

    In this case, X is kept constant and the masses of the two bodies are increased to 2m12m_1 and 2m22m_2. So, the gravitational force will become F=2m1.2m2X2,thatis,F=4m1.m2X2F'= \dfrac { 2m_1.2m_2 }{ { X }^{ 2 } } ,\quad that\quad is,\quad F'= 4\dfrac { m_1.m_2 }{ { X }^{ 2 } } .

             that is F=4FF'=4F

    Hence, the magnitude of the gravitational force between them will increase be 44 times. 

  • Question 6
    1 / -0
    A fruit (mass =50g= 50 g) falls from a tree because of gravitational attraction between the earth and the fruit. Which of the following statements is true if x is the force exerted by the earth on the fruit and y is the force exerted by the fruit on the earth?
    Solution
    Gravitational force is a mutual attraction between two bodies. 
    F=Gm1m2r2F=G\dfrac{m_1m_2}{r^2} where m1m_1 and m2m_2 are the masses of the two bodies and r the distance between them. 
    The body m1m_1 attracts the body m2m_2 with a force FF towards it and vice-versa.
    Hence x and y will be equal but acting in opposite directions.
  • Question 7
    1 / -0
    The weight of an object on earth is 800 N. If it were taken to the moon, it would weight 100N. What is its mass on the moon? (Acceleration due to gravity on earth = 10 ms2^{-2})
    Solution
    Answer:Answer:- A
    Mass on earth=weightacceleration due to gravityMass\ on\ earth=\dfrac { \text {weight} }{ \text {acceleration due to gravity} }

    Mass=80010=80 KgMass=\dfrac{800}{10}=80\ Kg

    Since mass depends on the matter in the body so independent of what the gravity is so it is 80 kg on earth as well as on moon.
  • Question 8
    1 / -0
    An object placed on the ground has a gravitational force of 160160 N acting on it. What is the weight of the object? (g=10m/s2 {g= 10 m/s^2} )
    Solution
    The weight of an object on the ground is defined as a force by which the earth pull this object. In this given question, the gravitational force on an object is 160 N, which mean that the earth is pulling this object towards centre by a force of 160 N. 
    Hence the weight of object on the ground will be 160 N.
    Option D. 
  • Question 9
    1 / -0
    A jet plane flies in air because 
    Solution
    Initially , when the plane is taking off, thrust force is more than the force of gravity. When it is in the air, the force of  gravity is compensated by the thrustof the jet. 
    And when the plane lands, at that point of time , the thrust force is less than the force of gravity.
  • Question 10
    1 / -0
    If the mass of a body on the surface of the earth is 50 kg50\ kg, its mass at the centre of the earth is:
    Solution
    The mass of the object does not change by moving it to another place.Mass is invariant of the body location.Mass is amount of matter present in body which is constant. At the center of the earth the net gravitational force is zero, so the weight will be zero, but its mass will remain same.Hence the mass at the centre of earth will be equal to 50 kg.
Self Studies
User
Question Analysis
  • Correct -

  • Wrong -

  • Skipped -

My Perfomance
  • Score

    -

    out of -
  • Rank

    -

    out of -
Re-Attempt Weekly Quiz Competition
Self Studies Get latest Exam Updates
& Study Material Alerts!
No, Thanks
Self Studies
Click on Allow to receive notifications
Allow Notification
Self Studies
Self Studies Self Studies
To enable notifications follow this 2 steps:
  • First Click on Secure Icon Self Studies
  • Second click on the toggle icon
Allow Notification
Get latest Exam Updates & FREE Study Material Alerts!
Self Studies ×
Open Now