Short Answer TypeA stone of mass' is rotated in a circular path with a uniform speed by tying a strong string with the help of your hand. Answer the following questions:
(i) Is the stone moving with a uniform or variable speed?
(ii) Is the stone moving with a uniform acceleration? In which direction does the acceleration act?
iii) In which direction is the force acting on the stone?
(i) As given in the question, the stone is moving with uniform speed.
(ii) Although the stone is rotating with uniform speed, its direction keeps on changing. Hence, the stone is said to be moving with uniform acceleration. The direction of acceleration is towards the centre of the circle.
(iii) The force which acts on the hand is the centrifugal force. Its direction is opposite to the centripetal force, i.e. away from the centre.
From the diagram given below, answer the question that follow:
(i) What kind of pulleys are A and B?
(ii) State the purpose of pulley B.
(iii) What effort has to be applied at C just raise the load L = 20 kgf? (Neglect the weight of pulley A and friction)
(i) An effort is applied on the bigger wheel of a gear having 32 teeth. It is used to turn a wheel of 8 teeth. Where it is used.
(ii) A pulley system has three pulleys. A load of 120 N is overcome by applying an effort of 50N. Calculate the Mechanical Advantage and Efficiency of this system.
(i) What is the principle of method of mixtures?
(ii) What is the other name given to it?
(iii) Name the law on which the principle is based?
Some ice is heated at a constant rate, and its temperature is recorded after every few seconds, till steam is formed at 100o C. Draw a temperature time graph to represent the change. Label the two phase changes in your graph.
A copper vessel of mass 100 g contains 150 g of water at 50o C. How much ice is needed to cool it to 5o C?
Given:
Specific heat capacity of copper = 0.4 J g-1o C-1
Specific heat capacity of water = 4.2 J g-1o C-1
Specific latent heat of fusion ice = 336 Jg-1
(i) Write a relationship between angle of incidence and angle of refractions for a given pair of media.
(ii) When a ray of light enters from one medium to another having different optical densities it bends. Why does this phenomenon occur?
(iii) Write one conditions where it does not bend when entering a medium of different optical density.
A lens produces a virtual image between the object and the lens.
(i) Name the lens.
(ii) Draw a ray diagram to show the formation of this image.
What do you understand by the term’ Scattering of light’? Which colour of white light is scattered the least and why?
(i) Name the waves used for echo depth sounding.
(ii) Give one reason for their use for the above purpose.
(iii) Why are the waves mentioned by you not audible to us?
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