Waec 2020 Physics Past Questions And Answers
A 60kg man stands on a weighing balance in an elevator. If the elevator accelerates upwards at 5ms\(^{-2}\), determine the reading of the scale. [g = 10ms\(^{-2}\)]
- A. 300N
- B. 600N
- C. 800N
- D. 900N
A motorcycle starting from rest is uniformly accelerated such that its velocity in 10s is 72kmhr\(^{-1}\). What is its acceleration?
- A. 108ms\(^2\)
- B. 86ms\(^2\)
- C. 4ms\(^2\)
- D. 2ms\(^2\)
The length of an iron bar is 100cm at 20°C. At what temperature will its length increase by 0.01%? [Linear expansivity of iron = 1.2 x 10\(^{-5}\)°C]
- A. 48.0°C
- B. 38.0°C
- C. 28.3°C
- D. 23.0°C
A 500N box rests on a horizontal floor. A constant horizontal force is exerted on the box so that it moves through 8m. If the coefficient of kinetic friction between the floor and the box is 0.22, calculate the workdone on the box
- A. 880J
- B. 440J
- C. 400J
- D. 110J
A bullet is fired from a gun at 30\(^o\) to the horizontal. The bullet remains in flight for 25s before touching the ground. Calculating the velocity of projection. [g = 10ms\(^{-2}\)]
A moving-coil galvanometer which gives a full-scale on deflection with 0.005A is converted to a voltmeter reading up to 5V using an external resistance of 975Ω. What is the resistance of the metre?
- A. 0.25Ω
- B. 2.50Ω
- C. 25.00Ω
- D. 250.00Ω
In a solar panel for heat supply, state the function of each of the following parts: (a) metal flat plate; (b) thermal insulator: (c) tubes.
A parallel plate capacitor is charged and the charging battery is subsequently disconnected. lf the plates of the capacitor are moved farther apart by means of insulating handles, the
- A. capacitance would increase
- B. capacitance would decrease
- C. charge on the capacitor would increase
- D. charge on the capacitor would decrease
Which of the following statements about the process of melting of a solid are true? The temperature of the solid will
I. remain steady until melting starts.
ll. keep rising until melting starts,
Ill remain steady as melting proceeds.
V, keep rising as melting proceeds.
- A. II and llI only
- B. IlI and IV only
- C. I, Il and Ill only
- D. ll and IV only
The diagram below illustrates a beam of parallel rays from a distant object O, incident on one side of the total reflecting prism. Which diagram does not represent the correct path of the beam when it emerges from the prism?
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- A. W
- B. X
- C. Y
- D. Z