WAEC 2016 physics obj and theory

Physico -obj

1CCBBCBDBCD

11 DACADCAADB

21 BACBBBDDBD

31 DDDBDABABA

41 BCAADABCDC

Physico -Answers

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8a )

Net force: The net force is the vector sum of all the forces that act upon an object . It is also the sum of all the forces, taking into account the fact that a force is a vector and two forces of equal magnitude and opposite direction will cancel each other out .

8b )

The law of conservation of linear momentum states that the total

momentum of a system of particles remains constant , so long as no

external forces act on the system.

e . g Firing a bullet from a gun or a radioactive nucleus spontaneously emitting an alpha particle .

8c )

M = 200 g = 0 .2kg , h = 2cm , h2 = 1.8 m , u = 0, v =?

P .E = mgh

P .E = K .E = 1/ 2 MV ^ 2

4 = 1 / 2 x 0. 2 x V ^ 2

V = √ 40 = 6. 32 m / s ^ -1

Impulse = M 0

Impulse = 0. 2 6.32)

= 1.264 Kgms ^ -1

8d )

M = 0. 02 kg , f= 5 Hz , x = 10 cm = 0.1 , V = 200 cm = 2 m / s

8dii )

r = ? , w = 2πf = 2 x3 .142 x 5

W = 31 .4

From V = w √ r^ 2 - 0 .1^ 2

2 = 31 . 4 √ r^ 2 - 0 .1 ^ 2

= r^ 2 - 0 .1^ 2 = 0 .6369^ 2

r^ 2 = 0.41564161

r = √ 0 .41564161

r = 0. 64 m

Maximum vel

V = wr (x = 0 at maximum )

8diii)

maximum potential energy

=1 / 2 MVm^ 2

=1 / 2* 20 ^ 10 * (372 .3 )^ 2

=10 * 138596 .4

=1385964 J

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10 a )

Critical angle is the angle of incidence in the optically densed medium when the angle of refraction is 90 degrees

10 b)

Anti-note are created by region of maximum displacement in a wave

more coming

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11 a )

Dielectric strength is the property of an insulating material to retain material to retain electrical properties

11 bi)

-Infra-red wave

-Geiger muller counter

-Scintillation counter

11 bii )

Irradiation of solar energy

11 c )

Charge (q )=1. 0* 10 ^ - 19C

Electric field intensity(E )=1200NC^ - 1

Weight of the oil drop =?

E = F / q

1200=F / 1. 0* 10 ^ -19

F = 1200* 1. 0* 10 ^ -19

F = 1.2 * 10 ^ 3* 10^ -19

F = 1.2 * 10 ^ -16 N

11 d)

R =100 ohm , L = 0.05 H , C =0. 25 uF

V =220 v , f= 50 Hz

11 di)

Impedance (z )=sqroot 0^ 2)

Xl = 2* pie * fl

Xl = 2* 3.1428571428571* 50 * 0. 05

Xl = 15. 71 ohm

Xl = 0

Xc =1/ 78. 55 * 10 ^ -6

Xc =10 ^ 6/ 78. 55

=12730 .7ohm

Z= sqroot -12630.7

Z= sqroot (10000+2 .63 * 10 ^ 16

Z= sqroot 26.3

Z= 1.62 * 10 ^ 16 ohm

11 dii )

Vrms= IZ

I =220 / 1.62 * 10 ^ 16

=1 .36 * 10 ^ -14

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9a )

i) thermal equilibrium is the point at which the temperature of an object remain constant or steady

ii )fundamental interval is the distance between upper and lower fixed point of a thermometre

9b )

i) it can be used to raise heavy load

ii ) it is used in printing press

9c )

magnet

9di )

by using calometry law

heat last = heat gain

MmCmDθm= CaDθ + Mw Cw Dθ

300 * Cm * 45 = 90 + 500 * 4200

13500Cm = 90 + 29400000

13500CM = 29400090/ 13500

Cm =2177.78 Jg^ -K ^ -1

9dii ) §

i) by convection

ii ) by conduction

9diii) §

i) power generation

ii ) chemical processing

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5)

i) For launching astronauts into the space

ii ) For launching satellite

iii ) For Scientific research

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6a )

Doping is the addition of small quantity of an element to a semi conductor to change its characteristics

6b )

Doping introduce impurities into an extremely pure instrintic semi conductor for the purpose of modulating its elctrical properties

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7)

X = Electron gun

Y = Accelerating mode

Z = Deflection plate

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3)

-smoke

-aerosol

-dust particle

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1a )

impulse (I )=F * t

F = ma = m v= M d)

f= M l/ T )= MLT^ -2

I =MLT^ - 2 * T

I =MLT^ - 1

1b )

Acceleration(a )= v/ t=d/ t

a = d/ t^ 2 = L / T ^ 2= LT^ - 2

1c )

WOrk(w )=f* d

W = MLT^ -2 * L

W = ML ^ 2T ^ -2

(Note : This symbols ^ means Raise to power)

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