WAEC 2019 PHYSICS OBJ & ESSAY VERIFIED ANSWERS

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PHYSICS OBJ:
1-10: CBBBCACBCB
11-20: CCCABBBDCD
21-30: CCDADCDDDA
31-40: BDDBBCAABC
41-50: ABDABDBCBA

NOTE:
* means multiplication
/ means division
^ means raise to power
? means square root

(10)
FULL IMAGE – CLICK HERE

(11)
CLICK HERE FOR THE IMAGE

(1)

Mass = 20g = (20/100)kg = 0.02kg

Extension = 5cm = (5/100)m = 0.05m

K = 200N/

V = ?

1/2mv² = 1/2ke²

V = ?ke²/m = ?200×0.05×0.05/0.02

V = ?25

V = 5m/s

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<i.< b=””>(2a)
P is initial velocity in m/s
? is angle of projection
H is maximum height
R is Range

(2b)
R = P²sin2?/g
at maximum range, sin2? = 1
=> Rmax = p²/g
This happens at ? = 45degree</i.<>

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(3)

(i)reflection

(ii)refraction

(iii)diffraction 

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(4)

(i)Magnetic Declination

(ii)Horizontal Component of Earth’s Magnetic Field

(iii)The angle of Dip or Magnetic Inclination

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(5a)

Free electrons are electrons in a material which can contribute to electric current.

(5b)

hole is the absence of an electron in a particular place in an atom

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(6a)

Principle of operation of fiber optics state that the density of transparent glass and the refractive index is greater than the density of the two mirrors

(6b)

(i)it is used to view deep down the throat of a patient

(ii)it is used to conveying information

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(8ai)

It state that every particles in the universe attract every other particle with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them

(8aii)

Gravitational field is a region of space around a mass on which the gravitational force of the mass can be felt

(8bi)

F=GMeM/re^2 ——from newton’s law

Where Me is mass of earth

re is the distance of mass from earth

G is a constant of gravitation 

But F=GMeM/re^2 =mg

Me=GMe/re^2=g

g=GMe/re^2

(8bii)

(i)That The earth is a sphere

(ii)That g depends on mass of earth alone

(8c)

Using F = GMeM/r^2

F=6.67*10^-11*5.98*10^24*2.00*10^3degree/(1.50*10^8*10^3)^2

F= 79.7732*10^43/2.25*10^22

F=35.455*10^21

=3.5455*10^22N

(8di)

Escape velocity (Ve) is the minimum velocity required for an object (egg statelite) to just escape or leave the gravitational influence or field of an astronomical body (eg earth) permanently 

(8dii)

(i)g varies across the earth but G is constant 

(ii)the unit of g is m/s^2 while that of G is NM^2/Kg^2

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9ai)
Latent heat , energy absorbed or released by a substance during a change in its physical state (phase) that occurs without changing its temperature . The latent heat associated with melting a solid or freezing a liquid is called the heat of fusion ; that associated with vaporizing a liquid or a solid or condensing a vapour is called the heat of vaporization . The latent heat is normally expressed as the amount of heat (in units of joules or calories ) per mole or unit mass of the substance undergoing a change of state.

(9aii)

(i)surface area in contact with atmosphere

(ii)nature of the liquid

(9bi)

Clay is poorer conductor of heat than plastic

(9bii)

An increase in pressure in the cooker increase the ambient temperature in the cooker hence the food cooks faster

(9c)

(i)Change in the state of a substance

(ii)Increase in temperature

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(10a)

Atomic spactra is  the spectra of frequencies of electromagnetic radiation emitted or absorbed during transitions of electrons between energy levels within an atom.

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(11ai)

Force is anything that causes motion.Its S.I unit is Newton(N) or Kgm/s^2

(11aii)

(i) Static friction

(ii) Dynamic friction

(11bi)

DRAW THE GRAPH

(11bii)

Deceleration

during last 5s=18/5=3.6m/s^2

(11biii)

Total distance=S1+S2+S3+S4

=(30*20)+1/2(18+30)(6)+(18*10)=(1/2*5*18)

=600+144+180+45

=969metres

Posted by admin on 3rd May 2019.

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Categories: WAEC