Post Utme Physics Past Questions and Answers

Question 176:

A light of energy \(5 \mathrm{eV}\) falls on a metal and electrons with a maximum kinetic energy of \(2 \mathrm{eV}\) are ejected. The work function of the metal is ____________

A. \(0.4 \mathrm{eV}\)
B. \(2.5 \mathrm{eV}\)
C. \(3.0 \mathrm{eV}\)
D. \(7.0 \mathrm{eV}\)

Question 177:

One of the features of fission process is that ____________

A. Its products are not radioactive
B. It leads to chain reaction
C. Neutrons are not released
D. The sum of the masses of the reactants equals the sum of the masses of the products

Question 178:

A body of mass \(5 \mathrm{~kg}\) initially at rest is acted upon by two mutually perpendicular forces \(12 \mathrm{~N}\) and \(5 \mathrm{~N}\) as shown in the figure below. If the particle moves in the direction QA, calculate the magnitude of the acceleration.

[image]

A. \(2.60 \mathrm{~m} / \mathrm{s}^{2}\)
B. \(0.26 \mathrm{~m} / \mathrm{s}^{2}\)
C. \(3.40 \mathrm{~m} / \mathrm{s}^{2}\)
D. \(1.40 \mathrm{~m} / \mathrm{s}^{2}\)

Question 179:

A car of mass \(1500 \mathrm{~kg}\) goes round a circular curve of radius \(50 \mathrm{~m}\) at a speed of \(40 \mathrm{~m} / \mathrm{s}\).
The magnitude of centripetal force on the car is ____________

A. \(1.2 \times 10^{2} \mathrm{~N}\)
B. \(1.2 \times 10^{3} \mathrm{~N}\)
C. \(4.8 \times 10^{3} \mathrm{~N}\)
D. \(4.8 \times 10^{4} \mathrm{~N}\)

Question 180:

The efficiency of a machine is always less than \(100 \%\) because ____________

A. Load lifted is always greater than work input
B. Load lifted is always greater than the applied effort
C. Effort applied is always greater than mechanical advantage
D. Velocity ratio is always greater than the mechanical advantage