CIE IGCSE Physics Solved Past Paper May/June 2020 P42
1 ai) distance in speed-time graph=area under the graph
Graph has three rectangles and so their area is equal to distance.
First convert time from minutes to hours to have all values in same units
Therefore distance = (5*20/60)+(40*20/60)+(6+22/60)
ii) speed = distance from previous calculation/time in hours
b) acceleration=change of speed/change of time which is equal to the gradient
c) as speed remains constant,no acceleration takes place so acceleration=0
2a) impulse = force*time = change in momentum = m(v-u)
b) force = change in momentum/time taken
c) the streamlined shape of the train reduces air resistance
d) less air resistance for slower speed so higher time taken to stop train
e) water droplets decrease friction
3a) change in temperature = energy taken by water/mass of water*specific heat capacity of water
Energy = power*time,power needed to raise temperature of water is calculated by:(power output/power input)*100 = efficiency
Power output = (20*5000)100
Energy = 1000*3600
Change in temperature = 3.6*10^6/4200*15
b) solar panels don’t burn fossil fuels which means no emissions of any harmful gas so it reduces air pollution.
As the main energy source is sun,absence of it at night means no energy supply.
4a) Place the thermometer in crushed melting ice.The point where liquid stops moving is the lower fixed point.Place thermometer in steam and the point where liquid stops moving is the upper fixed point.
b) Liquid is frozen at 90?
c i)thinner bore (ii)longer tube
d i)uniform expansion
5a) by marking a normal along barrier,measure angle of incidence draw a reflected ray with angle of reflection same as angle of incidence.
6a) straight incident ray into the prism and reflected ray perpendicular to
b) n=1/sinC n=1/(sin45)=1.41
7 aii) iron is easily magnetised and demagnetised.The u shaped magnet
links magnetic field of both coils
iii) current in primary coil=I2*V2/V1=(0.1*2)/12=0.017 ohm
b) metal case should be earthed to prevent electrocution in case live wire
8b) resistance=V/I=3.1/0.03=100 ohm
c) (i) V=10.5-2.1=8.4
b i) AND ii) 0,1,1,1
c) charge = current*time
Number of electrons=180/1.6*10^-19=1.1*10^21
10a) lead gives direction by absorbing most of radiation
b i) out of page because alpha particles are same as conventional
ii) into the page because beta particles are same as conventional
current in opposite direction
iii) goes straight because dues to absence of charge means no effect
of magnetic field