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Water balloons are dropped from the top of a very tall building by the managemen

ID: 249780 • Letter: W

Question

Water balloons are dropped from the top of a very tall building by the management of the Santa Cruz Bowling Academy as a nonviolent deterrent to loitering. Each water balloon has a mass of 0.5 kg and a terminal velocity of 25 m/s. (a) When the rst balloon hits the ground, the impact time (i.e. the time it takes for the balloon to come to a stop) is 0.05 s. Calculate the acceleration of the balloon as it comes to a stop. (b) Use what you found in part (a) to calculate the net force on the balloon during impact. (c) The loiterers respond by placing pillows on the ground. The eect that this has is to increase the impact time to 0.4 seconds. Find the new acceleration of the balloons and the net force during impact.

Explanation / Answer

mass of 0.5 kg

velocity of 25 m/s

time = 0.05 s

(a) final velocity = 25,

initial velocity =0

and t= 0.05sec;

hence,

F.dt = mv

F = 0.5*25/0.05 = 250 N.

a = F/m = 500 m/s2.

(b)

force *time = change in momentum;

t=0.05

force = 0.5*(25-0)/0.05 = 250N

(c)

here t = 0.4 and every thing remains same

F.dt = mv

F = 0.5*25/0.4 = 31.25 N.

a = F/m = 62.5 m/s2.