2018 Waec Gce Physics Theory & Obj Answers

2018 Waec Gce Physics Theory & Obj Answers [expo]

2018 Waec Gce Physics Theory & Obj Answers [expo]

 

Physics – Obj
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(1a)
Young modulus of a material or the modulus of elasticity.

(1b)
Potential Energy to kinetic Energy.

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(2)
e = 0.7m
m=60 × 10^-3kg = 6.0×10^-2kg
K = 200Nm^-1
W = 1/2ke² = 1/2mv²
1/2ke² = 1/2mv²
V² = ke²/m = 200×0.7²/6.0×10^-2
V² = 98×10²/6
V² = 16.33×10²
V = √1633
V = 40.4
Speed = 40.4ms^-1

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(3)
(i) Optical fibres have extremely high bandwidth
(ii) They have longer transmission distance
(iii) They have resistance to electromagnetic interference

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(4a)
It is used in geometric stations used to move a satellite from low earth orbit into a geostationary orbit.

(4b)
Polar orbit satellite is used in earth mapping.

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(5a)
(i) Centripetal force
(ii) Centrifugal force

(5b)
Ft = mDv
where F = force
t = time
Dv = change in velocity
m = mass of object

Hence F = mDv/t

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(6a)
(i) It can cause short and long term sun burn effects.
(ii)It can cause blindness when flashed to the eyes.

(6b) Energy = hf
= 6.60×10^-34 × 4.82×10^14
= 3.18×10^-19J
= 1.99ev

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(7)
V = 2πR/T
R = 9.6×10^6 + 6.4×10^6 =16×10^6 m
T = 24hrs =(24×60×60)s
V = 2×3.142×16×10^6/24×60×60
V = 1162.96m/s
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8a) Mass is the amount of material contained in a body and the SI unit is Kg while Weight is the force exerted on a body by the gravity of the object. ..Mass is a scalar quantity( It has not specific direction), While Foce is a vector quantity (Its in the same direction with gravity)

8ai
Mass is measured in Kg
Weight is measured in Newton
Mass is a scalar quantity
Weight is a vector quantity
Mass is constant
Weight varies

8aii) Clockwise moment about the pivot.
Moment = Force x Distance
Moment = 250 x 0.75
Moment = 187.5Nm

8bii (the value of F)
Clockwise moment = Anti clockwise moment
Fx(1.5+0.75) + 50x 0.75 = 250 x 0.75
F x 2.25 + 37.5 = 187.5
2.25F = 187.5-37.5
2.25F= 150
F = 150/2.25
F= 170.83N

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