A stone is thrown at $45^\circ$ on level ground with speed $u = 10$ m/s. Using $g = 10$ m/s$^2$, the range is:
A$5$ m, the height reached, not the range covered
B$20$ m, twice the launch speed in metres
C$10$ m, since $R = u^2\sin 90^\circ/g = 100/10$
D$2.5$ m, one quarter of the launch speed
Answer & Solution
Correct answer: C. $10$ m, since $R = u^2\sin 90^\circ/g = 100/10$
$R = u^2\sin 2\theta/g = 100\cdot 1/10 = 10$ m.