Post Utme Physics Past Questions and Answers

Question 576:

A reservoir \(500 \mathrm{~m}\) deep is filled with a fluid of density \(850 \mathrm{kgm}^{-3}\). If the atmospheric pressure is \(1.05 \times 10^{5} \mathrm{Nm}^{-2}\), the pressure at the bottom of the reservoir is ____________

\[ \left[\mathrm{g}=10 \mathrm{~ms}^{-2} \right] \]

A. \(4.72 \times 10^{6} \mathrm{Nm}^{-2}\)
B. \(4.36 \times 10^{6} \mathrm{Nm}^{-2}\)
C. \(4.28 \times 10^{6} \mathrm{Nm}^{-2}\)
D. \(4.25 \times 10^{6} \mathrm{Nm}^{-2}\)

Question 577:

A string of length \(4 \mathrm{~m}\) is extended by \(0.02 \mathrm{~m}\) when a load of \(0.4 \mathrm{~kg}\) is suspended at its end. What will be the length of the string when the applied force is \(15 \mathrm{~N} ?

\left[\mathrm{~g} 10 \mathrm{~ms}^{-2} \right]\)

A. \(4.05 \mathrm{~m}\)
B. \(4.08 \mathrm{~m}\)
C. \(5.05 \mathrm{~m}\)
D. \(6.08 \mathrm{~m}\)

Question 578:

A turning fork of frequency \(340 \mathrm{~Hz}\) is vibrated just above cylindrical tube of height \(1.2 \mathrm{~m}\), if water is slowly poured into the tube at what maximum height will resonance occur?

[speed of sound in air \(=340 \mathrm{~ms}^{-1}\) ]

A. \(0.45 \mathrm{~m}\)
B. \(0.95 \mathrm{~m}\)
C. \(0.60 \mathrm{~m}\)
D. \(0.50 \mathrm{~m}\)

Question 579:

A wire of \(50 \Omega\) resistances is drawn out so that its new length is twice the original length. If the resistivity of the wire remains the same and the cross-sectional area is halved, the new resistance is ____________

A. \(200 \Omega\)
B. \(50 \Omega\)
C. \(40 \Omega\)
D. \(100 \Omega\)

Question 580:

An electron of charge \(1.6 \times\) \(10^{-19}\) is accelerated between 2 metal plates. If the kinetic energy of the electron is \(4.8 \times 10^{-17} \mathrm{~J}\), the potential difference between the plates is ____________

A. \(300 \mathrm{~V}\)
B. \(30 \mathrm{~V}\)
C. \(400 \mathrm{~V}\)
D. \(40 \mathrm{~V}\)