Question : A rifle is aimed horizontally at a target 30 m away. The bullet hits the target 1.9 cm below the aiming point. What are
(a) the bullet's time of flight and
(b) its speed as it emerges from the rifle
Doubt by Girisha
Solution :
Here
h=1.9 cm
h=1.9/100 m
h=19/1000 m
Range (R) = 30 m
(a) We know,
T=√[2h/g]
T=√[2(19/1000)/9.8]
T=√38/9800]
T≈0.0623 sec
Hence, the time of flight of bullet is approximately equals to 0.06 sec
(b)
R=u√[2h/g]
R=uT
R/T = u
u = 30/0.0623
u ≈ 481.54 m/s
Hence, speed of the bullet as it emerge from the rifle would be 481.54 m/s.