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3-2.Motion in Plane
hard
A particle is projected with a velocity of $30\,m / s$, at an angle of $\theta_0=\tan ^{-1}\left(\frac{3}{4}\right)$ After $1\,s$, the particle is moving at an angle $\theta$ to the horizontal, where $\tan \theta$ will be equal to $\left(g=10\,m / s ^2\right)$
A
$1$
B
$2$
C
$\frac{1}{2}$
D
$\frac{1}{3}$
Solution
(d)
$u_x=u \cos \theta_0=20 \times \frac{4}{5}=24\,m / s$
and $\quad u_y=u \sin \theta_0=30 \times \frac{3}{5}=18\,m / s$
After $1 s , u_x$ will remain as it is $u_y$ will decreases by $10\,m / s$ or it will remain $8\,m / s$
$\therefore \quad \tan \theta=\frac{v_y}{v_x}=\frac{8}{24}=\frac{1}{3}$
Standard 11
Physics