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प्रश्न
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
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उत्तर
The gravitational force and the reaction force in the vertical direction have the same magnitude. Friction is not action as the horizontal surface is smooth.
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संबंधित प्रश्न
A ball is thrown vertically upwards with a velocity of 49 m/s. Calculate
- the maximum height to which it rises.
- the total time it takes to return to the surface of the earth.
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.
State whether the following statement is true or false :
The acceleration due to gravity acting on a freely falling body is directly proportional to the mass of the body.
Fill in the following blank with suitable word :
The acceleration due to gravity on the moon is about ………………of that on the earth.
What do you mean by the term free fall ?
Explain why, if a stone held in our hand is released, it falls towards the earth.
The values of g at six distances A, B, C, D, E and F from the surface of the earth are found to be 3.08 m/s2, 9.23 m/s2, 0.57 m/s2, 7.34 m/s2, 0.30 m/s2 and 1.49 m/s2, respectively.
(a) Arrange these values of g according to the increasing distances from the surface of the earth (keeping the value of g nearest to the surface of the earth first)
(b) If the value of distance F be 10000 km from the surface of the earth, state whether this distance is deep . inside the earth or high up in the sky. Give reason for your answer.
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.
A force of 15 N acts on a body of mass 2 kg. Calculate the acceleration produced.
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
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.
Define the term acceleration due to gravity? Write its S.I. unit.
How is the acccelaration due to gravity on the surface of the earth realted to its mass and radius ?
How are g and G realated ?
What is escape velocity?
Write the acceleration due to gravity value on the surface of Earth.
Write a short note.
Escape Velocity
The mass and weight of an object on earth are 5 kg and 49 N respectively. What will be their values on the moon? Assume that the acceleration due to gravity on the moon is 1/6th of that on the earth.
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?
