Post Utme Physics Past Questions and Answers

Question 1146:

A $75g$ ice cube at $0^{\circ }C$ is placed in $825g$ of water at 25 ${}^{\circ }C$. What is the final temperature of the mixture? [S.L.H ice $=3.33\times {10}^{5}J/kg$, S.H.C water \(\left.=4200 J / kgk \right] .

A. \cdot 10^{\circ} C\)
B. ${12}^{\circ }C$
C. ${15}^{\circ }C$
D. ${16}^{\circ }C$

Question 1147:

Sound travels with a different speed in media. In what order does the velocity of sound increase in these media?

A. Water, iron and air
B. Iron, air and water
C. Air, water and iron
D. Iron, water and air

Question 1148:

Railway tracks are banked on curves

A. Necessary centrifugal force may be obtained from the horizontal component weight of the train
B. To avoid frictional force between tracks and wheels
C. Necessary centripetal force may be obtained from the horizontal component of the weight of the train
D. The train may not fly off in the opposite direction

Question 1149:

Optical fibre works on the

A. Principle of refraction
B. Total internal refiection
C. Scattering
D. Interference

Question 1150:

A wall made of wood $4.0cm$ thick has area of $48.0m^2$. If the temperature inside is ${25}^{\circ }C$ and the temperature outside is ${14}^{\circ }C$, at what rate is thermal energy transported by conduction?
[Thermal conductivity $k$ for wood $=0.08W{m}^{-1}{k}^{-1}$ ].

A. $82W$
B. $210W$
C. $690W$
D. $1100W$