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प्रश्न
Write scientific reasons.
The value of gravitational acceleration (g) is taken to be -g when studying the motion of an object thrown upwards in a straight line.
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उत्तर
- For the motion of an object thrown upwards, the magnitude of g is the same throughout the motion, but the velocity of the object decreases with the increase in height.
- For an object thrown upwards, the direction of acceleration due to gravity is opposite to the velocity of the object.
Hence, the value of gravitational acceleration (g) is taken to be -g when studying the motion of an object thrown upwards in a straight line.
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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 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.
What is the acceleration produced in a freely falling body of mass 10 kg ? (Neglect air resistance)
What do you understand by the term 'acceleration due to gravity of earth' ?
A pressure of 10 Pa acts on an area of 3.0 m2. What is the force acting on the area ? What force will be exerted by the application of same pressure if the area is made one-third ?
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?
The total energy of an object falling freely towards the ground ______.
A force acts for 10 s on a stationary body of mass 100 kg, after which the force ceases to act. The body moves through a distance of 100 m in the next 5 s. Calculate : The acceleration produced by the force
How are g and G realated ?
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 force, in newton, your muscles need to apply to hold a mass of 5 kg in your hand? State the assumption.
What is escape velocity?
In vacuum, all freely falling objects have the same force. Is it true?
The free fall of an object is possible only in ______.
Write the acceleration due to gravity value on the surface of Earth.
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?
When is free fall possible?
