1999 - JAMB Physics Past Questions and Answers - page 1
Power = Force x (\frac{distance}{time}) = (\frac{m(v - u)}{t} \times v)
(\frac{800(25 - 0)}{20} \times 25) = 2.5 x 10 4 watts
Users' Answers & CommentsY = stress/strain, but stress = 107Nm-2 (given).
Strain = e/l0. = (10.05 - 10.00)/10.00 = 0.005
Thus Y = 107/0.005 = 2 . 0 x 109Nm-2
Users' Answers & CommentsR.D = loss in weight in liquid X loss in weight in water.
R.D = (10 - 7)/(10 - 6) = 3/4
Users' Answers & CommentsAt constant T, P1 V1 = P2 V2.
Let P1 = P0 and V1 = V0, then solve accordingly.
Users' Answers & CommentsEnergy at the height = mgh
This energy is converted to heat energy - mcΔt
∴ From the principle of energy conversion,
mcΔt = mgh
m x 450 x Δt = m x 10 x 20
∴ Δt = m x 10 x 20/(m x 450)
= 200/450
= 4/9°C
Users' Answers & CommentsII. Dissolved substances in pure water lead to increase in the boiling point.
III. When the external pressure is increased, the boiling point increases.
IV. Dissolved substances in pure water decrease the boiling point.
Which combination of the above are peculiarities of the boiling point of a liquid?
Temperature Gradient = (\frac{\Delta {\text{temp.}}}{\text{thickness}})
= (\frac{80 - 20}{0.02})
= (\frac{60}{0.02})
= 3000Km-1
= 3.0 x 103Km-1
Users' Answers & CommentsSpecific heat capacity of copper = 400JKg-1K-1
Latent heat of fusion of ice = 3.3 x 105JKg-1
Heat given off by the copper = MCt
= 2 x 400 x (100 - 0)
Heat absorbed by the ice = ML
= M x 3.3 x 105
Heat lost = Heat gained
∴ M x 3.3 x 105 = 2 x 400 x 100
∴ M = (2 x 400 x 100)/3.3 x 105
= 8/33Kg
Users' Answers & Comments