Question

An object of mass 10 kg is projected from ground with speed 40 m/s at an angle ${60}^o$ with horizontal. The rate of change of momentum of object one second after projection in SI unit is [Take $g=9.8m/s^2$]

• A. 73
• B. 98
• C. 176
• D. 140

Answer 1

The correct option is B 98

After $1$ sec
$u_x$ remains same
$=ucos{60}^{\circ }=40\times \frac{1}{2}=20$
$u_y^{\prime }=usin{60}^{\circ }-g\left(1\right)$

$=40\times \frac{\sqrt{3}}{2}-9.8$

$=20\sqrt{3}-9.8$

$\Delta p=m(u_y^{\prime }-u_y)$

$=10(20\sqrt{3}-9.8-20\sqrt{3})$

$=10\times -9.8$

$=-98$

$|\Delta P|=98$ kg-m/s