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Name a machine to change the point of application of force ?
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In which of the following cases, is work being done?
(i) A man pushing a wall.
(ii) a coolie standing with a load of 12 kgf on his head.
(iii) A boy climbing up a staircase.
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Express joule in terms of erg.
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1 J = ______ calorie.
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Differentiate between energy and power.
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A boy of mass 40 kg climbs up the stairs and reaches the roof at a height 8 m in 5 s. Calculate:
- the force of gravity acting on the boy,
- the work done by him against the force of gravity,
- the power spent by boy. (Take g = 10 m s-2)
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It takes 20 s for a person A of mass 50 kg to climb up the stairs, while another person B does the same in 15 s. Compare the Work done.
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A weight lifter lifted a load of 200 kgf to a height of 2.5 m in 5 s. Calculate:
- the work done, and
- the power developed by him. Take g = 10 N kg-1
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A machine raises a load of 750 N through a height of 16 m in 5 s. calculate:
- energy spent by machine,
- power at which the machine works.
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A boy of weight 40 kgf climbs up the 15 steps, each 15 cm high in 10 s and a girl of weight 20 kgf does the same in 5 s. Compare:
- the work done, and
- the power developed by them. Take g = 10 N kg-1.
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A water pump raises 50 litres of water through a height of 25 m in 5 s. Calculate the power of the pump required.
(Take g = 10 N kg-1 and density of water = 1000 kg m-3)
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Name the forms of energy which a wound-up watch spring possesses.
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Name three factors on which the deviation produced by a prism depends and state how does it depend on the factors stated by you.
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How does the deviation produced by a triangular prism depend on the colours (or wavelengths) of light incident on it?
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Which colour of white light travels fastest in glass?
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In following figure shows a thin beam of white light from a source S striking on one face of a prism.
Complete the diagram to show effect of prism on the beam and to show what is seen on the screen.
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In following diagram shows a thin beam of white light from a source S striking on one face of a prism.
A slit is placed in between the prism and the screen to pass only the light of green colour. What will you then observe on the screen?
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In following diagram shows a thin beam of white light from a source S striking on one face of a prism.
What conclusion do you draw from the observation in part (b) above?
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If a monochromatic beam of light undergoes minimum deviation through an equiangular prism, how does the beam pass through the prism, with respect to its base?
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(i) Draw a diagram to show the splitting of white light by a prism into its constituent colour.
(ii) Draw another diagram to show how the colours of spectrum of white light can be combined
to give the effect of white light.
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