# Physics 1st Paper CQ-Dhaka Board-2017

প্রশ্ন ·সময় ২ ঘণ্টা ৩৫ মিনিট

1. A simple pendulum is taken to a hill, It completes 11990 full oscillations in 10 hours. But in-plane field, it completes ant oscillation in 3 seconds. The average radius of earth is $6400 \mathrm{~km}$ and the height of Mount Everest is $8.854 \mathrm{~km}$. [The gravitational acceleration is $9.8 \mathrm{~ms}^{-2}$ ]

DB 17
ব্যাখ্যা আনলক করতে চর্চা প্রিমিয়াম এ আপগ্রেড করো

2. In a high rise Building-a lift having a capacity of $400 \mathrm{~kg}$ take people from $1^{\text {st }}$ floor to $6^{t /}$ floor. The height of each floor is $3 \mathrm{~m}$. The mass of a person in that office is $45 \mathrm{~kg}$. One day he measures his weight in a machine inside the lift when the lift was moving at an acceleration of $2 \mathrm{~ms}^{-2}$. The acceleration due to gravity was $9.8 \mathrm{~ms}^{-2}$.

DB 17
ব্যাখ্যা আনলক করতে চর্চা প্রিমিয়াম এ আপগ্রেড করো

3. According to the figure the initial length of a wire $A$ is $1 \mathrm{~m}$ and cross-sectional area $1 \mathrm{~mm}^{2}$. On the other hand, Young's modulus of a wire $B$ having $2 \mathrm{~m}$ length is $1.2 \times 1011 \mathrm{Nm}^{2}$. One of the wire is comparatively thick and the other. is more elastic. The increase in lymph due to applied force is shown in the graph. An object is bound by one wire and pulled by another write.

DB 17
ব্যাখ্যা আনলক করতে চর্চা প্রিমিয়াম এ আপগ্রেড করো

4. Sumon and Rana, two friends see that, an object was thrown from $O$ point at $32 \mathrm{~ms}^{-1}$ velocity having an angle $30^{\circ}$ covers $2 \mathrm{~m}$ high wafl $A B$ covering horizontal distance $85 \mathrm{~m}$ and falls down.

DB 17
ব্যাখ্যা আনলক করতে চর্চা প্রিমিয়াম এ আপগ্রেড করো

5. The above figure shows the change in gravitational acceleration from the centre of the earth. The mass of earth is $M=6.0 \times$ $10^{24} \mathrm{~kg}$ and radius of earth is $R=6400 \mathrm{~km}$.

DB 17
ব্যাখ্যা আনলক করতে চর্চা প্রিমিয়াম এ আপগ্রেড করো