Solutions to SQA examination

1997 Higher Grade Physics

Paper I Solutions

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1. B		11. A			21. C
2. C		12. B			22. E
3. A		13. E			23. D
4. D		14. A			24. D
5. D		15. A			25. C
6. C		16. B			26. D
7. B		17. A			27. A
8. A		18. C			28. E
9. C		19. A			29. D
10.A		20. E			30. E

31.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: FDirection of travel= FResultantcos20o FDirection of travel= 150xcos20o FDirection of travel= 140.95N The total force from both ropes (Ftotal) can now be calculated. Ftotal= 2x140.95N Ftotal= 281.9N b. 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. Ffriction= -281.9N (-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 [Ek(before)] and the [Ek(after)] must be considered. Elastic collision => Kinetic energy conserved. Inelastic collision => Kinetic energy not conserved. Before collision Total [Ek(before)]= 0.036J +0J Total [Ek(before)]= 0.036J Total [Ek(after)]= 0.009J +0.018J Total [Ek(after)]= 0.027J Kinetic energy is not conserved, therefore, the collision is inelastic. 34.a. Wave period(T) = 4x2.5ms T = 10x10-3s f=1/T f=1/10x10-3s f=100Hz b. 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 = V m = -r x = I c = E m = (4-1)/(1-3) = 3/-2 = -1.5 =>r = -m = 1.5 =>r = 1.5W b. I = E/r E is the emf of the battery, found by noting where the graph cuts the voltage axis. E = 5.5V =>I = 5.5/1.5 I = 3.67A 36.a. The refractive index of paraffin(np) is found by calculating the ratio of the speed of light in air to the speed of light in paraffin. np = 3x108/2.1x108 np = 1.43 b. The frequency of the light is unchanged when moving from air into paraffin. f=4.85x1014Hz 37.

38. The spectrum produced by the prism is a result of refraction, whereas the grating produces a spectrum as a result of diffraction. Furtheremore, only one spectrum of white light is produced using a prism, whereas, several are produced using a diffraction grating.


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