A Level Physics ### CIE A Level Physics Solved Past Paper May/June 2020 P21

1 bii) A random error is a human error like not taking readings correctly and a systematic error could be with the apparatus that you are using like here with analogue ammeter, a zero error is systematic error but this won’t be the case with digital ammeter.

2 bi) When the parcel is vertically above point P, it has a vertical initial speed of zero and acceleration due to free fall with positive magnitude since air resistance is negligible thus, the direction of acceleration is vertically downwards.

ii) You have the parcel’s vertical initial speed, its acceleration, and time taken for it to travel to horizontal ground i.e. 0.81s. REMEMBER time interval for horizontal and vertical component will be equal.

iii) Horizontal distance requires horizontal speed with which parcel travels and its constant as well as time interval which is 0.81s.

cii) In the previous case, the only force that acted on the parcel was its own weight which was also the resultant force on that parcel. Now this parcel has two forces both acting in opposite directions and air resistance increases with increase in parcel’s speed. As a result resultant force starts to decrease over the course of time. When resultant force decreases, acceleration of the parcel decreases too.

iii) The conversion is NOT from g.p.e to k.e. because terminal speed means the parcel is at a constant speed so there has been no increase in k.e.. Instead due to significant air resistance, the parcel’s g.pe. converts to thermal energy.

3 bii) The wire is being pulled by two forces and both need to be taken into account to calculate stress for this wire. The best way is to take the resultant of these two forces (2.4N and F) NOT the sum of them as they are perpendicular to each other.

ci) Position A to B is an arc from point P that means both AP and BP are radius. BP=75cm

4 bii) Intensity shares no relationship with fringe separation and this directly affects brightness or darkness of fringes. Reducing intensity of the light increases the brightness of dark fringes and reduces the brightness of bright fringes.

5 bii) Cross-sectional area has a relationship with resistance of wire which in this case increases in the part which is thinner. Power is directly proportional to resistance and so power dissipation is greater in thinner part.

cii) The potential divider gives an output voltage of 8.0V however, we do not have any idea whether this voltage is across the single resistor or the parallel connection. You must try fitting your three resistors (180, 90 & 30 ohms) in such a way that either side gets 8.0V and the remaining voltage across the other connection.