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A light ray suffers reflection and refraction at the boundary in passing from air to water. Draw a neat labelled ray diagram to show it.
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The speed of light in air is 3 × 108 m s-1. Calculate the speed of light in glass. The refractive index of glass is 1.5.
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(i) Write one advantage of connecting electrical appliances in parallel combination.
(ii) What characteristics should a fuse wire have ?
(iii) Which wire in a power circuit is connected to the metallic body of the appliance ?
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Give an example for each of the following uses of a machine:
to change the point of application of force
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Give an example of the following uses of a machine:
to change the direction of force
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One joule is the amount of work done when a force of ......... moves a body through a distance of .......
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What is the work done when no net force is applied on the body?
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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.
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Calculate the resultant moment of forces about O and state its direction in fig.
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Fig. 5 shows a uniform meter scale weighing 200 gf. Provided at its centre. Two weights 300 gf and 500 gf are suspended from the ruler as shown in the diagram. Calculate the resultant torque of the ruler and hence calculate the distance from mid-point where a 100 gf should be suspended to balance the meter scale.
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(i) What do you understand by the term couple of forces?
(ii) Calculate the moment of a couple shown in fig.
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Three forces A, B and C are acting on a rigid body which can turn about O in fig.9. If all the three forces are applied simultaneously, in which direction will the body move? Explain.
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Fig. shows a uniform meter scale weighing 100 N pivoted at its centre. Two weights of 500 N and 300 N are hung from the ruler as shown in fig.
(i) Calculate total clockwise and anticlockwise moments.
(ii) Calculate difference in clockwise moment and anticlockwise moment.
(iii) Calculate the distance from O where a 100 N weight should be suspended to balance the meter scale.
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