(i) Complete the following by choosing the correct answers from the bracket: (a) A _______ M.A. > 1.[class I/class II/Class III] lever will always have (b) In a block and tackle system, increase in the weight of the movable ______ [decreases, does not affect, increases] the block efficiency of the pulley system. (c) If the mass as well as the velocity of a body is doubled then the kinetic energy of the body______ [is doubled/becomes eight times/becomes four times] the initial kinetic energy. (d) Unit of power used in mechanical engineering is _____[watt/horse power/erg per second] (e) Two copper wires can have the different _____[resistivity/resistance] but will have same _____[resistance /resistivity]
(ii) Draw a graph of potential energy vs height for a body thrown vertically upwards. [Assume no friction is present.]
(iii) (a) Name the waves used for echo depth sounding. (b) Give one reason for their use in the above purpose.
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