IGCSE Physics

### 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)

= 17.2

?17km

ii) speed = distance from previous calculation/time in hours

= 17.2/1.2

= 14km/h

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)

= 750000(84-42)

=31500000

?3.2*10^7 N/s

b) force = change in momentum/time taken

= 31500000/80

=393750?3.9*10^5N

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

= E/M*C

Energy = power*time,power needed to raise temperature of water is calculated by:(power output/power input)*100 = efficiency

Power output = (20*5000)100

=1000W

Energy = 1000*3600

=3.6*10^6J

Change in temperature = 3.6*10^6/4200*15

= 57?

b) solar panels donâ€™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.

b) frequency=speed/frequency

=1.2/0.36=3.3Hz

c) sound,compressions

6a) straight incident ray into the prism and reflected ray perpendicular to

incident ray.

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

touches case

8b) resistance=V/I=3.1/0.03=100 ohm

c) (i) V=10.5-2.1=8.4

R=8.4/1.5=5.6 ohm

ii)P=VI=8.4*1.5=12.6W

9a)  1,1,1,0

b i) AND    ii) 0,1,1,1

c) charge = current*time

= 3*60

=180C

Number of electrons=180/1.6*10^-19=1.1*10^21