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प्रश्न
When is free fall possible?
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उत्तर
Free fall is only conceivable in the absence of air or vacuum. When a ball and a feather are thrown from a height, the ball falls to the ground first. In a vacuum, both the ball and the feather will end up on the ground.
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संबंधित प्रश्न
A stone is thrown vertically upward with an initial velocity of 40 m/s. Taking g = 10 m/s2, find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?
A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s. Calculate when and where the two stones will meet.
Fill in the following blank with suitable word :
The acceleration due to gravity on the moon is about ………………of that on the earth.
Explain why, if a stone held in our hand is released, it falls towards the earth.
Explain why, a wide steel belt is provided over the wheels of an army tank.
Explain why, the tip of a sewing needle is sharp.
Name the force which wears away two surfaces as they move over one another.
Name the force which stops you falling through the floor.
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?
For freely falling object we can write the Newton’s second equation of motion as …..
What would be the value of ‘g’ on the surface of the earth if its mass was twice and its radius half of what it is now?
The value of acceleration due to gravity of earth :
A body is projected vertically upward with an initial velocity u . If acceleartion due to gravity is g , the time for which it remains in air , is :
What is escape velocity?
State whether the below statement is True or False.
Neglecting air resistance, a body falling freely near the earth's surface has a constant acceleration.
The mass of planet ‘X’ is four times that of the earth, and its radius is double the radius of the earth. The escape velocity of a body from the earth is 11.2 × 103 m/s. Find the escape velocity of a body from the planet ‘X’.
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?
