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DELHI PUBLIC SCHOOL NEWTOWN SESSION 2021-22 MONDAY TEST CLASS: X SUBJECT: PHYSICS FULL MARKS: 40 DATE: 26.07.2021 General Instructions: This paper consists of two printed pages. All questions are compulsory. Copy the question number carefully before answering the questions. Marks will be deducted for spelling errors. Question 1 [2+2+2+2+2] (a) State the energy changes in the following: i) Burning of a candle ii) Loud speaker when in use (b) A ball of mass 200 g is thrown upward with initial velocity 20 ms-1. At what height above the ground the ball would have equal kinetic and potential energy? [g = 10 m/s2] (c) If the kinetic energy of a body is increased by 4 times, by how much does its linear momentum change? (d) A cone has height 24 cm. Locate its centre of gravity from the vertex if the cone is i) solid ii) hollow (e) State the conditions for equilibrium of a body. Question 2 [2+2+2+2+2] (a) Why is the handle of a grinding stone of a hand grinder placed near the rim of the stone? (b) The power of a motor is 40 kW. At what speed can it raise a load 20000 N? (c) Which physical quantity does electron-volt measure? How is it related to the SI unit of the same quantity? (d) A crane A lifts a heavy weight in 5 s, whereas another crane B does the same work in 2 s. Compare the power of the two cranes. (e) Can a couple acting on a rigid body produce translatory motion? Justify tour answer. Question 3 (a) Determine the magnitude of x, if the rod is in equilibrium. 1 [4 +3 +3] (b) A rubber ball of mass 250 g is dropped from a height of 20 m. Calculate i) The velocity of the ball with which it hits the ground ii) The kinetic energy of the body at its half-way point. (g = 10 m/s2) (c) Why are the railway wagons not loaded beyond a certain limit? State one point of difference between uniform linear motion and uniform circular motion. Question 4 [4+3+3] (a) A force is being applied on a pivoted body. Show two conditions with the help of diagrams, by which the direction of rotation can be altered. (b) Determine the nature of work done (positive, negative or zero) done on the body in the given cases: i) Work done by the weight when a body is displaced along a horizontal surface. ii) When a ball falls freely under the action of gravity. iii) When two similar charges get repealed by each other. (c) A bullet of mass 50 g, moving at 400 m/s pierces through a wooden block of thickness 50 cm. If the average retarding force exerted by the block is 3500 N, then with what velocity will the bullet come out? 2
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