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प्रश्न
State two conditions when the work done by a force acting on a body is zero.
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उत्तर
(i) When there is no displacement by the force in the body.
(ii) When the displacement is normal to the direction of the force.
संबंधित प्रश्न
State the condition when a body is in dynamic equilibrium.
State two condition for a body acted upon by several forces to be in equilibrium.
The figure shows a uniform metre rule placed on a fulcrum at its mid-point O and having a weight 40 gf at the 10 cm mark and a weight of 20 gf at the 90 cm mark.
- Is the metre rule in equilibrium? If not how will the rule turn?
- How can the rule be brought in equilibrium by using an additional weight of 40 gf?
A faulty balance of equal arms but pans of unequal weight is used to find the weight of a body. By the method of double weighing the weights are found as 8 kg and 8.2 kg. Find the actual weight of the body.
The arms of a beam balance are 20 cm and 21 cm, but the pans are of equal weight. By the method of double weighing the weights are found to be 1000 g and 20 g. Find the actual weight of the body
In figure, a uniform bar of length l m is supported at its ends and loaded by a weight W kgf at its middle. In equilibrium, find the reactions R1 and R2 at the ends.
`["Hint:" "In equilibrium" "R"_1 + "R"_2 = "W" "and" "R"_1 xx l/2 = "R"_2 xx l/2]`
What do you mean by dynamic and static equilibrium? Give one example of each.
A ball is placed on a compressed spring. When the spring is released, the ball is observed to fly away.
(i) What form of energy does the compressed spring possess?
(ii) Why does the ball fly away?
Explain the types of stability with suitable examples.
