Question

a raindrop with a mass of 1 mg falls at 3 m/s when there is no wind. find its kinetic energy when a wind of 5 m/s is blowing.

Answer 1

Find it's kinetic energy using the kinetic energy formula for 3 m/s and then for 2 m/ s since that's the difference between 3 and 5 and then add them up.

Answer 2

sorry but @mihirb is wrong
you may find the vector sum of the velocities which comes out to be (34)^1/2
and then substitute it in the formula k.e.=(mv^2)/2
so you may get the answer=10^-6 x 34 / 2 = 1.7 x 10^-5 J

Answer 3

K.E. = (1/2)mv^2

Assuming the wind is horizonal to the ground,

v = Sqrt( Vx^2 + Vy^2 )
= Sqrt(5^2 + 3^2)
= Sqrt(34)
= 5.83 m/s

mass = 1 milligram
= 1.0*10^(-3) gr
= 1.0*10^(-6) kg

K.E. = (1/2)*(1.0*10^(-6))*(5.83)^2
= 17 x10(-6) (kg m/s^2)