A projectile is fired from the top of a 40 m high chit with an initial speed of 50 m/s at an unknown angle. Find its speed when it hits the ground.
Height from where the projectile is fired, h = 40 m
Initial speed of the projectile, u = 50 m/s
Final speed at which the projectile hits the ground = v m/s
Acceleration due to gravity, g = 10 m/s2
Using the equation of motion, v2 - u2 = 2gh
⇒ v2 = u2 + 2gh
⇒ v2 = 502 + 2×10×40
⇒ v2 = 2500 + 800
⇒ v2 = 3300
⇒ v = 57.45 m/s
∴ The projectile hits the ground with a speed of 57.45 m/s