Physics 2008 Waec Past Questions and Answers

Question 16 :

• WAEC 2008

An object of mass 0.25kg moves at a height h above the ground with a speed of 4ms^-1, if its mechanical energy at this height is 12 J, determine the value of h. [g = 10ms^-1]

A. 0.8m
B. 4.0m
C. 4.8m
D. 5.6m

Question 17 :

• WAEC 2008

Which of the following equations for the efficiency of a machine is correct?

A. Efficiency = \(\frac{\text{Velocity Ratio}}{\text{Mechanical Advantage}}\) x 100%
B. Efficiency = \(\frac{input}{output}\) x 100%
C. Efficiency = \(\frac{\text{load distance}}{\text{effort distance}}\) x 100%
D. Efficiency = \(\frac{\text{Mechanical Advantage}}{\text{Velocity Ratio}}\) x 100%

Question 18 :

• WAEC 2008

The design of the thermostat of an electric iron is based on the

A. Emmision of electrons from metals when heated
B. Increase in size of metals when heated
C. Increase in the density of metals when heated
D. Change in the mass of metals when heated

Question 19 :

• WAEC 2008

A metal rod of length 50cm is heated from 40^oC to 80^oC. If the linear expansivity of the material is \(\alpha\), calculate the increase in length of the rod (in metres) in terms of \(\alpha\)

A. 20\(\alpha\)
B. 200\(\alpha\)
C. 2000\(\alpha\)
D. 20000\(\alpha\)

Question 20 :

• WAEC 2008

The cubic expansivity of a certain gas at constant pressure is \(\frac{1}{273} k^{-1}\). If a given mass of the gas is held at constant pressure and its volume at 0^oC is 273m³, determine the volume of the gas at 273^oC.

A. 273m³
B. 546m³
C. 819³
D. 1092³