# Physics 1st Paper CQ-Dinajpur Board-2019

প্রশ্ন ·সময় ২ ঘণ্টা ৩৫ মিনিট

1. At room temperature in a definite place a cylinder of volume $0.6 \mathrm{~m}^{2}$ is filled up with $800 \mathrm{gm}$ methane $\left(\mathrm{CH}_{4}\right)$ gas with pressure $202650 \mathrm{pa}$. A teacher said to his students that the dew point of this place is $11.5^{\circ} \mathrm{C}$ and there is a possibility of rain if the relative humidity of that place is more than $60 \%$. At $11^{\circ} \mathrm{C}$, $12^{\circ} \mathrm{C}, 19^{\circ} \mathrm{C}$ and $20^{\circ} \mathrm{C}$ the saturated vapour pressure are 9.84 $\mathrm{mm}(\mathrm{Hg}), 10.52 \mathrm{~mm}(\mathrm{Hg}), 16.46 \mathrm{~mm}(\mathrm{Hg})$ and $17.54 \mathrm{~mm}$ $(\mathrm{Hg})$. The molecular mass of methane is $16 \mathrm{gm} / \mathrm{cc}$.

Din.B-19
ব্যাখ্যা আনলক করতে চর্চা প্রিমিয়াম এ আপগ্রেড করো

2. The length of a spring increases $2 \mathrm{~cm}$ due to application of $80 \mathrm{gm}$ mass and increases its length $8 \mathrm{~cm}$ due to $600 \mathrm{gm}$ mass. Aroni observed $1 \mathrm{~cm}$ length expansion from its equilibrium position of the above spring.

Din.B-19
ব্যাখ্যা আনলক করতে চর্চা প্রিমিয়াম এ আপগ্রেড করো

4. The equation of a sound wave produced by a tuning fork 'A' is $y=0.7 \sin \pi(500 t-1.47 x)$. All quantities mentioned in this equation are expressed in S.I unit. Another tuning fork ' $B$ ' made unison with the fundamental note created by the wire of sonometer having length $0.25 \mathrm{~m}$. The wire of the sonometer is pulled with a force $5 \mathrm{~kg}$.wt and the mass of the length $1 \mathrm{~m}$ wire is $3 \mathrm{gm}$.

Din.B-19
ব্যাখ্যা আনলক করতে চর্চা প্রিমিয়াম এ আপগ্রেড করো

5. Three forces act on a body of mass $2 \mathrm{~kg}$ at a point $O$ for $4 \mathrm{~s}$ according to the figure-1. Later only $5 N$ and $6 \mathrm{~N}$ forces is acting on the same body for 4s.

Din.B-19
ব্যাখ্যা আনলক করতে চর্চা প্রিমিয়াম এ আপগ্রেড করো