Dr. Han is waiting on a tow truck after his carbage\'s engine blew up. To pass t
ID: 1329895 • Letter: D
Question
Dr. Han is waiting on a tow truck after his carbage's engine blew up. To pass the time he tosses a tennis ball straight up to a maximum height of 136 meters. The diameter of a ball is 7.3 cm and its mass is 141 g. The density of air is 1.23 mg/cm3 and the coefficient of drag is 0.53.
As Dr. Han waits for the ball he ignores air resistance and calculates the theoretical speed of the ball if he catches it 2 meters off of the ground. What is this theoretical speed?
Feeling sorry for Dr. Han, Lazy Dog factors in air resistance and calculates the terminal speed of the ball. What is it?
Dr. Han is waiting on a tow truck after his carbage's engine blew up. To pass the time he tosses a tennis ball straight up to a maximum height of 136 meters. The diameter of a ball is 7.3 cm and its mass is 141 g. The density of air is 1.23 mg/cm3 and the coefficient of drag is 0.53.
Explanation / Answer
initial height of the ball = yo = 136 m
the ball is catche dat 2 m height , y1 = 2
initial velocity at maximum heigth = vo = 0
v1^2 - vo^2 = 2*ay*dy
v1^2 - 0 = 2*(-9.8)*(-134)
v1 = 51.2 m/s
+++++++++++++++++++
when the weight of the ball is balanced by drag force
Fd = Fg
Fd = 0.5*rho*Cd*A*v^2
Fg = m*g
A = area = 4*pi*r^2
r = radius = 7.3 cm = 3.65 cm
m = 0.141 kg
0.5*1.23*0.53*4*pi*0.0365^2*v^2 = 0.141*9.8
v = 15.9 m/s
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