Consider a drop of rain water having mass 1 g falling from a height of 1 km. It hits the ground with a speed of 50 ms^(-1). Take .g. constant with a value 10 ms^(-2). The work done by the (i) gravitational force and the (ii) resistive force of air is

Consider a drop of rain water having mass 1 g falling from a height of

1.	Consider a drop of rain water having mass 1 g falling from a height of 1 km. It hits the ground with a speed of 50 ms^(-1). Take .g. constant with a value 10 ms^(-2). The work done by the (i) gravitational force and the (ii) resistive force of air is
Answer» (i) `1.25 J "" `(II) `-8.25 J` (i) `100 J ""` (ii) `8.75 J` (i) `10 J "" ` (ii) `-8.75 J` (i) `-10 J "" ` (ii) `- 8.25 J` Solution :Here, `m = 1 g = 10^(-3) kg, h = 1 km= 1000m`, `v =50 ms^(-1), g = 10 ms^(-2)`. (i) The work done by the gravitational force `= mgh = 10^(3) XX 10 xx 1000 = 10 J` (ii) The total work done by gravitational force and the resistive force of air is equal to charge in kinetic energy of rain DROP. `:. W_g + W_r = 1/2 mv^2 - 0` v `10 + W_r = 1/2 xx 10^(-3) xx 50 xx 50 " or W_r = - 8.75 J`.