What is the ball's mass?

A 22 cm diameter bowling ball has a terminal speed of 77 m/s. What is the ball's mass?

Here is the work I have done that is incorrect according to mastering physics.

Vterm = sqrt(4mg/pA)


Vterm = terminal velocity

m = mass

g = gravity

d = density of air

A = area of bowling ball

From the equation, we can see that we can find (or are given) all variables but the mass. To get area, we take half of the diameter (radius) and solve A = 4(pi)r^2 = 4(pi)(0.11 m)^2 = 0.152053 m^2.

According to my textbook, the density of air is 1.22 kg/m^2.

So plugging in the variables we get:

77 m/s = sqrt(4*x*9.8 m/s^2)/(1.22 kg/m^2*0.152053 m^2)

Solving for x (mass), I calculated 28.0576 kg, or 28 kg for 2 significant figures. This is not correct.

What is going wrong?

Please help. Thank you.

2 answers

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