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प्रश्न
A tall building has wide foundations.
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उत्तर
Foundation of buildings are kept wide so that the weight of the building may act on a larger area. As a result, it will exert less pressure on the ground. This avoids sinking of building into the earth.
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संबंधित प्रश्न
Name the factors affecting the turning effect of a body
Name of S.I. unit of the rate of change in momentum.
A rocket is moving at a constant speed in space by burning its fuel and ejecting out the burnt gases through a nozzle. Answer the following
1) Is there any change in the momentum of the rocket? if yes, what causes the change in momentum?
2) Is there any force acting on the rocket? if yes, how much?
Give two examples of a couple's actions in our daily life.
The moment of a force of 10 N about a fixed point O is 5 N m. Calculate the distance of the point O from the line of action of the force.
Classify the following amongst contact and non-contact forces.
Frictional force
Two unlike forces (parallel) of 10 N and 25 N act at a distance of 12 cm. from each other. Find the point about which the body balance.
Assertion & Reasoning
- Assertion: The sum of the clockwise moments is equal to the sum of the anticlockwise moments.
- Reason: The principle of conservation of momentum is valid if the external force on the system is zero.
A person standing in front of a cliff fires a gun and hears its echo after 3 s. If the speed of sound in air is 336 ms−1.
- Calculate the distance of the person from the cliff.
- After moving a certain distance from the cliff, he fires the gun again, and this time the echo is heard 1.5 s later than the first. Calculate the distance that the person moved.
A nut is opened by a wrench of length 25 cm. If the least force required is 10 N, find the moment of force needed to turn the nut.
