Free 2017 waec physics answers

*Complete Physics obj*

1-10 CAABADACC

11-20 BAADDCBADA

21-30 CCBACBCBAB

31-40 ACADDBBBAC

41-50 BCDABCABCA









1)

decrease in height (h)

increase in time (t)

this shows that distance changes with time







2)given that U=15m3^-1

R=U* sqr2h/g

h=20m

g=10

R=15*sqr2*20/10

R=15*sqr40/10

R=15*sqr4

R=15*2=30m

R=30m




3 )

i ) Brownian motion

ii ) Atomic size

iii ) Expansion
















4)

L1=14cm F1=4N,F2=6N

L2=4cm, Lo=?

Using hooke's law

4/14-Lo*6/4-Lo

4(4-Lo)=6(14-Lo)

16-4Lo=64-6Lo

-4Lo+6Lo=64-16

2Lo=48

Lo=48/2

Lo=24Cm







5a)

i)force

ii)length




5b)

By increasing the density mosquitoes lavrva than the density of water




6i)Energy efficient- so far the best light for interior lighting.

ii)Low production cost (of tubes, not of the ballasts)

iii)Long life of tubes.

iii)Long life of tubes.




7 )

i ) It requires low voltage sources for it to function

ii ) It cannot be easily broken

iii ) It is cheaper and quite easy to manufacture





8b)If their distance and masses are doubled their corresponding force would also be doubled and the work done respectively

I.e.Workdone=Force * distance

Force= Mass * Acceleration

W= Mg * d

|

Increase




8d (i)pushing someone on a swing.




(ii)Tuning a radio to a particular frequency.

fissioning.

10a) A wave front is an imaginary surface passing through the points of a medium oscillatory in phase

10bi)Prismatic binoculars is used to see round cornersj

II) Prism Periscope is used to bend and reflect light

10bii)i) Refractive index of the glass prism

II) The angle of the incident of ray




11a A dielectric is an electrical insulator that can be polorised by an applied electric field.

11aii) GIVEN: A = 9.6 * 10^-3 M^2

d = 2.25 * 10^4

Eo = 8.85 * 10^-12 F/m

Er = 900

C = /

using; C = EoErA/d

capacity, C = 8.85*10^-12 * 900 * 9.6*10^-3/2.25 * 106-4

C = 33984 * 10^-11

C = 3.3984 8 10^7 F

C =0.344F

11bi) A voltmeter has a higher resistance because it is designed to limit the flow of current to practically zero to avoid voltage drop or less across it.

11bii) combined resistance Rt

Rt = (400 * 400/400 400) (800 * 800/800 800)

Rt = 200 400

Rt = 600ohms

current supplied by battery = r/Rt

= 6/600

= 0.01A

voltage drop across the resistance = 200 * 0.01

=2V

therefore the voltage reading is 6 -2

= 4V

11c) Equivalent resistance is:

Rt = 2 2 (2*2/2 2)

Rt = 4 1

Rt = 5ohms




12ai)Nuclear fission is a nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle, with the release of energy.

12aii)a)A graphite reactor is a nuclear reactor that uses carbon as a neutron moderator, which allows un-enriched uranium to be used as nuclear fuel.

12aii)b)Boron rods are used in

nuclear reactors to control the fission rate of uranium and plutonium. They are composed of chemical elements such as boron, silver, indium and cadmium that are capable of absorbing many neutrons without themselves fissioning.










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