Physics 1st Paper CQ-Dhaka Board-2023

1. A second pendulum gives correct time at the bottom of a mountain. But when the pendulum is taken to the top of the mountain, it moves 30s slow per hour. The radius of the earth is 6400km and acceleration due to gravity is 9 .8ms$^{-2}$.

2. The width of a road is 5m at particular place its radius of curvature is 80m. The difference of height of both sides of the road is 0.4m. A vehicle was moving with a velocity $54 \mathrm{kmh}^{-1}$ before crossing the turning.

3. The back glass of a car is inclined with the roof with an angle $30^{\circ}$. The car was moving on a road with velocity $\vec{v}=18 \hat{i}$. Suddenly, the rain started falling with a velocity $\overrightarrow{\mathrm{u}}=12 \hat{j}$.

4. Mimi and her classmate was examined in a laboratory taking 100gm methane gas whose molecular mass is 16gm mol in a cylinder on a excessive heat day of summer. In this situation of weather the teacher said there is a possibility of rain at any place by exceeding relative humidity 70%. The dew point and air temperature at that place are 12.5°C and 20.6°C. The saturated vapour pressure at 12°C, 13°C, 20°C and 21°C temperature are 10.85mmHg, 14.5mmHg, 18.5mHg and 20.55Hg respectively.

5. Two swimmers, take part in a swimming competition to cross a river of width $1 \mathrm{~km}$The first swimmer starts swimming with a velocity $6 \mathrm{kmh}^{-1}$ against current making an angle $60^{\circ}$ and the second swimmer starts swimming crosswide with a velocity $6 \mathrm{kmh}^{-1}$. The velocity of current is $3 \mathrm{kmh}^{-1}$.