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1.B11.A21.C2.C12.B22.E3.A13.E23.D4.D14.A24.D5.D15.A25.C6.C16.B26.D7.B17.A27.A8.A18.C28.E9.C19.A29.D10.A20.E30.E31.a. Each rope exerts a force in the direction of travel. To calculate the component of the force in the direction of travel use basic trigonometry. The force from each rope is: F

_{Direction of travel}= F_{Resultant}cos20^{o}F_{Direction of travel}= 150xcos20^{o}F_{Direction of travel}= 140.95N The total force from both ropes (F_{total}) can now be calculated. F_{total}= 2x140.95NFb. As the boat is moving at constant speed, and in a straight line, the frictional force must be equal in magnitude to the pulling but acting in the opposite direction to the pulling force._{total}= 281.9NF(-ve sign indicates direction) 32.a. b. Newton's first law states that: "an object will remain at rest or move with a constant velocity in a straight line unless acted upon by an unbalanced force". This means there are no unbalanced/resultant forces acting on the balloon, as it is at rest. 33. To determine the type of collision the kinetic energy before the collision [E_{friction}= -281.9N_{k}(before)] and the [E_{k}(after)] must be considered. Elastic collision => Kinetic energy conserved. Inelastic collision => Kinetic energy not conserved. Before collision Total [E_{k}(before)]= 0.036J +0J Total [E_{k}(before)]= 0.036J Total [E_{k}(after)]= 0.009J +0.018J Total [E_{k}(after)]= 0.027J Kinetic energy is not conserved, therefore, the collision is inelastic. 34.a. Wave period(T) = 4x2.5ms T = 10x10^{-3}s f=1/T f=1/10x10^{-3}sf=100Hzb. The amplitude of the waves displayed on the oscilloscope will be unchanged, but, five complete waves will now appear on the screen. 35.a. V = E-Ir or V = -rI + E Compare this to: y = mx + c y = Vm = -rx = I c = E m = (4-1)/(1-3) = 3/-2 = -1.5 =>r = -m = 1.5 =>r = 1.5Wb. I = E/r E is the emf of the battery, found by noting where the graph cuts the voltage axis. E = 5.5V =>I = 5.5/1.5I = 3.67A36.a. The refractive index of paraffin(n_{p}) is found by calculating the ratio of the speed of light in air to the speed of light in paraffin. n_{p}= 3x10^{8}/2.1x10^{8}nb. The frequency of the light is unchanged when moving from air into paraffin._{p}= 1.43f=4.85x1037.^{14}Hz

- The lamp produces photons of light that have an energy that can be calculated using the equation E=hf.
- Some of this energy is absorbed by the semiconductor material of the photodiode.
- The absorbed energy creates electron hole pairs in the photodiode that increases the conductivity of the photodiode.
- There is a reduction in the potential barrier at the pn junction and therefore a reduction in the voltmeter reading.