Question

A particle is projected is projected with $20\sqrt{2}$m/sec making an angle ${45}^{\circ }$ with the horizontal the second of the particle at time $t=1$ sec. after projection.

• A. $25m/sec$
• B. $20m/sec$
• C. $20\sqrt{2}m/sec$
• D. $10\sqrt{5}m/sec$

Answer 1

The correct option is D $10\sqrt{5}m/sec$

$\left(D\right)$

$u=20\sqrt{2},\theta ={45}^o$

$u_x=ucos\theta =20$

$u_y=usin\theta =20$

using: $v=u+at$

$v_x=u_x=20$

$v_y=u_y-gt$

$v_y=20-10\times 1$

$v_y=10$

$v=\sqrt{v_x^2+v_y^2}$

$v=10\sqrt{5}m/sec$