A boy drops a 0.50kg rock from a 22m bridge into the river . What is the final speed of the rock just before it hits the water ?
To find the final speed of the rock just before it hits the water, we can use the equation for free fall:
v^2 = u^2 + 2as
Where:
v = final velocity (unknown)
u = initial velocity (0 m/s, as the rock is dropped)
a = acceleration due to gravity (-9.8 m/s^2, as the rock is falling)
s = distance fallen (22 m)
Plugging in the values:
v^2 = 0^2 + 2(-9.8)(22)
v^2 = 0 + (-431.2)
v^2 = -431.2
Since the velocity cannot be negative, we take the positive square root:
v = √431.2
Calculating this value, we get:
v ≈ 20.8 m/s
Therefore, the final speed of the rock just before it hits the water is approximately 20.8 m/s.