A Ping-Pong ball has a mass of 2.3 g and a terminal speed of 9.1 m/s. The drag force is of the form bv2 What is the value of b?
At terminal velocity, drag force becomes equal to weight. Therefore:
weight = bv²
0.0023 x 9.81 = b x 9.1²
b = 2.72 x 10⁻⁴
Answer:
\(2.72\cdot 10^{-4} kg/m\)
Explanation:
The terminal speed is reached by an object in free fall when the force of gravity becomes equal to the air resistance:
\(W=R\)
This can be rewritten as
\(mg=bv^2\)
where
m is the mass of the object
g is the gravitational acceleration
b is the coefficient of the air resistance
v is the speed of the object
In this problem, we have m = 2.3 g = 0.0023 kg, g=9.8 m/s^2 and v=9.1 m/s. Substituting and re-arranging the equation we find
\(b=\frac{mg}{v^2}=\frac{(0.0023 kg)(9.8 m/s^2)}{(9.1 m/s)^2}=2.72\cdot 10^{-4} kg/m\)