2020/2021 WAEC/NECO Answers: 2021 NECO GCE. PHYSICS ANSWERS

(6a)

The reason why convex mirror is used as a driving mirror is because they give erect image of an object. 

(6b) 

V = 0.4ms-¹

f = 6Hz

Apply 

V = fΔ

Δ = v/f

=0.4/6 = 0.67m

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(1a)

An Artificial Satellite is an artificial object that is manufactured by humans and launched into the Earth’s orbit or in another planet’s orbit. These satellites revolve round the planets and provide all the information about the planet through satellite imagery.

(1b)

A multistage rocket consists of two or more sections called stages. Each state has a rocket engine and propellant.A rocket is multistage because Rocket travelling to space requires more than one engine. The reason is because it will require much large amount of fuel or propellant to gain the speed required to escape earth gravity

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(5a)

Heat Capacity (Cp) of a body is the quantity of heat required to raise the temperature of the body by 1 Kelvin.

(5b)

m=5kg, I=3.36×10^5Jkg-¹

H=5×3.36×10^5J

H=16.8×10^5J

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(9a) 

(i) Gravitational fields have no polarity at all, WHILE Magnetic field are polar field with a north and south polarity. 

(ii) They are both forces of nature. 

(9b) 

Pick any two

(i) Cobalt 

(ii) Nickal 

(iii) Certain alloys 

(iv) Steel 

(v) Iron

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15a)

lens law of electromagnetic introduction state that the individual emf is such as way  to oppose the direction of motion or change in producing it.

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(3a)

Amplitude of a simple harmonic motion is defined as the maximum distance that an object moves from its equilibrium position. 

(3b)

-Speed-

(i)Speed is how fast an object is moving. 

(ii)It is calculated by the displacement of space per a unit of time. 

(iii)speed does not deals on direction

-Velocity-

(i)Velocity is the rate at which an object changes position in a certain direction. 

(ii)It is calculated by the displacement of space per a unit of time in a certain direction.

(iii)Velocity deals with direction

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(8a)

It is the measure of how easily an electron

can flow in that given wire.

It depends on experiment temperature,

electron density, current density .

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(10a)

Surface tension is the force acting along the surface of a liquid,causing the liquid surface  to behave like a stretched elastic skin

(10b) 

Adhesion is the force of attraction between molecules of different kinds eg the molecules of water and glass *WHILE* Cohesion is the force of attraction between molecules of the same kind eg The molecules of water

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