Polaroid

PHYSICS OBJECTIVE
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1(a) Elastic limit is the point on a load/extension graph beyond which Hooke?s law is no longer obeyed. (b) Hooke?s law of elasticity states that the extension (e) in an elastic material (wire) is directly proportional to the force (load) applied, provided the elastic limit is not exceeded. 2. Matter is made up of molecules which are held together by intermolecular forces which make the molecules to vibrate about their mean positions giving the solids definite shape. 3(a) Surface tension is the property of a liquid which makes its surface behave as though covered by an elastic skin. (b) The surface tension of a liquid can be reduced by (i) Heating the liquid (ii) Addition of impurities such as oil, alcohol, soap, camphor, kerosene etc.
4(a) (b)(i) V = rw = 2.5 x 10-2 x 0.4? = 3.142 x 10-2m/s (ii) a = rw2 = 2.5 x 10-2 x (0.4?)2 = 3.95 x 10-2m/s (c) (i) k = w. H is the time rate of change of m angular displacement. H is measured in radians per second. (ii)(1) K.Emax = 1 MV2 max = 1 mr2w2 2 2 But w = k = w2 = k = 30 = 100 rad/s2 m m 0.3 ? K.Emax = 1 mr2w2 = 1 x 0.30 x (0.015)2 x 100 2 2 = 3.38 x 10-3 J (2) Tmax = Weight + Ke = Mg + Ke = 0.30 x 10 + 30 x 0.015 = 3.45N 5(a)(i) (i) Electric potential is the work done in moving a unit positive change from infinity to a point in an electric field. H is measured in volts of J/C. (ii) Electric potential unit is in volts v. Electric potential energy is matured in Joules (J) (b)(i) Electric field intensity E = Q 4??or2 (ii) Electric potential V = Q 4??or2 (iii) E = I OR E = Y V r 4??or2 (c)(i) E = v = 5 x 104 = 107v/m d 5 x 10-3 (ii) F = qE = 1.6 x10-19x107 = 1.6 x10-12N (iii) F = ma ? a = F = 1.6 x10-12 m 9.1x10-31 = 1.76 x 1018 m/s2
6(a)(i) In nuclear fission reaction results in splitting a heavy nucleus into two parts of nearly equal masses while in nuclear fusion process two light nuclei combine together to form a heavier nucleus. (ii) Nuclear fission releases less energy per nuclear while nuclear fusion releases more energy per nuclear. (iii) Nuclear fission can take place at room temperature while nuclear fusion takes place at very high temperature while nuclear fusion takes place at very high temperature. r d (ii) Peaceful uses of atomic energy are: - Production of laser beams ? Production of x-rays ? Production of energy in discharge tubes.
(b)(i). The neutrons produced as a result of fission of a nucleus can cause further fission if they strike other nuclei. This rapid multiplication of a fission process by fissile neutrons is called chain reaction. (ii) (i) Conditions necessary for chain reaction to occur are: - The mass of fissile material must exceed the critical mass ? In addition to the two nuclei produced during the fission, one to three neutrons must be produced per parent nucleus. (ii) Components in a nuclear reactor used to control chain reactions are ? Boron steel ? Heavy water or deuterium oxide ? Graphite or carbon rod.