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प्रश्न
Define force.
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उत्तर
Force is a physical cause that changes or may tend to change the state of rest or the state of motion of an object.
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संबंधित प्रश्न
Match the column
| Column A | Column B |
| (a) Camel | (1) broad and deep foundation |
| (b) Truck | (2) broad feet |
| (c) Knife | (3) six or eight tyres |
| (d) High building | (4) sharp cutting edge |
| (e) Thrust | (5) atm |
| (f) Moment of force | (6) N |
| (g) Atmospheric pressure | (7) N m |
State one way to decrease the moment of a given force about a given axis of rotation.
The steering wheel of a vehicle is of large diameter.
Find the moment of force of 20 N about an axis of rotation at distance 0.5 m from the force.
A wheel of diameter 2 m can be rotated about an axis passing through its center by a moment of force equal to 2.0 Nm. What minimum force must be applied on its rim?
What are non-contact forces? Give two example
A body X of mass 5 kg is moving with velocity 20 m s-2 while another body Y of mass 20 kg is moving with velocity 5 m S-1. Compare the momentum of the two bodies.
It is easier to turn the steering wheel of a large diameter than that of a small diameter. Given reason.
A uniform metre rule of weight 10gf is pivoted at its 0 mark.
What moment of force depresses the rule?
Classify the following amongst contact and non-contact forces.
gravitation force
Classify the following amongst contact and non-contact forces.
electrostatic force
What is the work done when no net force is applied on the body?
A wheel of diameter 3 m is shown in fig. 2 with axle at 0. A force F = 8 N is applied at Q in the direction shown in figure. Calculate the moment of force about:
(i) centre o, and
(ii) point p.
What is meant by the term ‘moment of force’? If the moment of force is assigned a negative sign then will the turning tendency of the force be clockwise or anti-clockwise?
A uniform metre rule rests horizontally on a knife-edge at the 60 cm mark when a mass of 10 gram is suspended from one end. At which end must this mass be suspended? What is the mass of the rule?
The diagram shows wheel O pivoted at point A. Three equal forces F1, F2 and F3 act at point B on the wheel.
- Which force will produce maximum moment about A?
- Give a reason for your answer in (a).
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.
