Physics 1st Paper CQ-Dhaka Board-2019

1. In the stem, a wave is moving and it hit any place and again it come back by reflecting, finally it makes a new wave.

[All unit express in S.I unit]

2. To take two wire of different materials ' $\mathrm{A}$ ' and ' $\mathrm{B}$ ' and length is $200 \mathrm{~cm}$ and area of cross section $1 \mathrm{~mm}^{2}, 10 \mathrm{~kg}$ of mass is hanging both of the wires. For this reason length increase for ' $\mathrm{A}$ ' wire is $7 \%$ and ' $B$ ' wire is $8 \% .\left[\mathrm{g}=9.8 \mathrm{~m} / \mathrm{s}^{2}\right]$

3. In cricket field, Ripon hit a ball and the ball gets $30 \mathrm{~m} / \mathrm{s}$ velocity and it travels maximum horizontal distance. At the same time a fielder moves with $10 \mathrm{~m} / \mathrm{s}$ to catch the ball and distance travels $40 \mathrm{~m} .\left[\mathrm{g}=9.8 \mathrm{~m} / \mathrm{s}^{2}\right]$

4. Raton is going to his grandfather's home to spend his summer vacation. At that place he sees a pendulum clock. This clock takes time 1 see to move left side to right side. When this clock takes in the mountain peak, it loses $120 \mathrm{sec}$.

[Radius of Earth, $\mathrm{R}=6450 \mathrm{~km}, \mathrm{~g}=9.8 \mathrm{~m} / \mathrm{s}^{2}$ ]

5. A car driver moving with $40 \mathrm{~km}$ per hour in the East direction and see a truck is moving with the double velocity count by hour in the North direction.

[Consider East direction in positive $\mathrm{x}$-axis and North direction in positive $y$-axis.]