The rain drop of mass 1 g, starts with zero velocity from a height of 1 km. It hits the ground with a speed of 5 m/s. The work done by the unknown resistive force is _______ J. (take g = 10 m/s ^2 )

Question

Quantrex Academy · Accepted Answer

Correct answer: D. -9.98

Using the work-energy theorem, the total work done by all forces equals the change in kinetic energy:

W_{g} + W_{r} = \Delta K

mgh + W_{r} = \dfrac{1}{2}mv^2 - 0

Substituting the given values (

m = 10^{-3}

kg,

g = 10

m/s

^2

,

h = 1000

m,

v = 5

m/s):

(10^{-3})(10)(1000) + W_{r} = \dfrac{1}{2}(10^{-3})(5)^2

10 + W_{r} = 0.0125

W_{r} = 0.0125 - 10 = -9.9875

J

W_{r} \approx -9.98

J

Answer:

-9.98

The rain drop of mass 1 g, starts with zero velocity from a height...

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