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प्रश्न
The free fall of an object is possible only in ______.
विकल्प
air
vacuum
on the surface of earth.
None of these.
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उत्तर
The free fall of an object is possible only in vacuum.
Explanation:
In air an object also feels drag, so its motion is not governed solely by gravity and is not true free fall. Only in a vacuum (no air) does an object accelerate under gravity alone, making the motion free fall.
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संबंधित प्रश्न
What do you mean by free fall?
A ball thrown up vertically returns to the thrower after 6 s. Find
- the velocity with which it was thrown up,
- the maximum height it reaches, and
- its position after 4 s.
Which force is responsible for the moon revolving round the earth ?
When an object is dropped from a height, it accelerates and falls down. Name the force which accelerates the object.
Explain what is meant by the equation :
`g= Gxxm/r^2`
where the symbols have their usual meanings.
During a free fall, will heavier objects accelerate more than lighter ones ?
What do you understand by the term 'acceleration due to gravity of earth' ?
What will be the weight of a person on earth, who weighs 9N on the moon?
A ball falls off a table and reaches the ground in 1 s. Assuming g=10 m/s2, calculate its speed on reaching the ground and the height of the table.
i) If g = GM/r2 then where will the value of g be high at Goa Beach or on top of Mount Everest?
A metal ball of mass 5 kg falls from a height of 490 m. How much time it will take to reach the ground? (g = 9.8 m/s2)
Choose one or more correct alternatives.
Which of the forces involved in dragging a heavy object on a smooth, horizontal surface, have the same magnitude?
- The horizontal applied force
- gravitational force
- reaction force in vertical direction
- force of friction
A force of 15 N acts on a body of mass 2 kg. Calculate the acceleration produced.
A car is moving with a uniform velocity 30 ms-1. It is stopped in 2 s by applying a force of 1500 N through its brakes. Calculate the following values : The retardation produced in car.
How are g and G realated ?
What is escape velocity?
Explain why:
Objects fall to the earth.
Right or wrong sentence.
Free fall of an object does not depend on the mass of the object.
Write scientific reasons.
When we drop a feather and a stone at the same time from a height the stone reach the earth faster than a feather.
Read the given passage carefully and answer the questions.
| We know that the force of gravity due to the earth acts on each and every object. When we were holding the stone in our hand, the stone was experiencing this force, but it was balanced by a force that we were applying on it in the opposite direction. As a result, the stone remained at rest. Once we release the stone from our hands, the only force that acts on it is the gravitational force of the earth and the stone falls down under its influence. Whenever an object moves under the influence of the force of gravity alone, it is said to be falling freely. Thus the released stone is in a free fall. In free fall, the initial velocity of the object is zero and goes on increasing due to the acceleration due to the gravity of the earth. During free fall, the frictional force due to air opposes the motion of the object and a buoyant force also acts on the object. Thus, true free fall is possible only in a vacuum. |
- Complete the following statement by choosing the right option.
The stone held in the hand is stable because on it ......- two unbalanced forces are exerted.
- only the gravitational force of the earth is exerted.
- gravitational force of the earth is not exerted.
- two balanced forces are exerted.
- Why does free fall not happen on the earth?
- Why does the velocity of the object increase during the free fall?
- Which type of force exerts on the object during free fall?
- Why does free fall happen only in a vacuum?
