An object falling through a fluid is observed to have acceleration given by a = g - bv, where g = gravitational acceleration and b, is constant. After a long time of release, it is observed to fall with constant speed. What must be the value of constant speed?


Hint: When speed becomes constant, acceleration, a = dvdt = 0.

Step1:Calculatespeedbyequatingacceleration=0. Given acceleration a=gbv

Clearly, from the above equation as speed increases acceleration will decrease. At a certain speed say V0, acceleration will be zero and speed will remain constant.

 Hence, a=gbv0=0v0=g/b