A rifle is aimed horizontally toward the center of a target 120 m away.If the bullet strikes 11.2 cm below the center,what was the velocity of the bullet? (Ignore air friction. )
A)23 m/s
B)1 120 m/s
C)32 m/s
D)790 m/s
E)400 m/s

Question

Quizplus · Accepted Answer

The bullet's vertical displacement is due to gravity, and its horizontal motion is constant. To find the bullet's velocity, we first calculate the time it took to fall 11.2 cm (0.112 m) under gravity. Using the formula $y = \frac{1}{2}gt^2$, where $g = 9.8 m/s^2$ and $y = 0.112 m$, we solve for $t$. Rearranging the formula gives $t = \sqrt{\frac{2y}{g}}$, which results in $t \approx 0.15 s$. Knowing the time and the horizontal distance (120 m), we can find the velocity using $v = \frac{d}{t}$, which gives $v \approx 800 m/s$. The closest answer provided is 790 m/s.

A Rifle Is Aimed Horizontally Toward the Center of a Target