Physics 1st Paper CQ-Chittagong Board-2021

1. A diver took a gas filled ballon to bottom of a $10 \mathrm{~m}$ depth lake and commented that the volume of the balloon at the bottom of the lake half of the surface. Atmospheric pressure $10^{5} \mathrm{Nm}^{-2}$ and density of the water of the lake is $1000 \mathrm{kgm}^{-3}$.

2. Half of a well of $16 \mathrm{~m}$ depth and $6 \mathrm{~m}$ diameter was filled with water. A pump of $2 \mathrm{~kW}$ power and $80 \%$ efficiency was used to empty the well. But the pump broke down after lifting half of the water. Another pump of $3 \mathrm{HP}$ power can empty the remaining water within 2 hours.

3. There are both meter gauge and broad gauge railways at the bend of a railway line of radius $500 \mathrm{~m}$. The distance between the two line of the meter gauge railway is 1 meter. The outer line is $6 \mathrm{~cm}$ higher than the inner line. The distance between the two line of the broad gauge railway is $1.3 \mathrm{~m}$, the outer line is $11 \mathrm{~cm}$ higher than the inner line.

4. Shanto is a student of a college. A river of wide $1 \mathrm{~km}$ flows by the side of his house. His college is straightly on the other side of the house. One day moming before 5 minutes to start the class, he left from house for college in a boat of velocity $12 \mathrm{kmh}^{-1}$ at $120^{\circ}$ angles with the current of the river.

5. In the figure the weight of the cylindrical shaped bar is $5 \mathrm{~kg}$ and the radius is $10 \mathrm{~cm}$. The bars of both the figure are rotating with velocity $1 \mathrm{rads}^{-1}$ along the rotational axis.