QA Work Energy and Power-3/ Work Energy Theorem
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The document discusses the work-energy theorem through an example of a falling raindrop with a mass of 1 gram from a height of 1 km, impacting the ground at 50 m/s. It calculates the work done by gravitational and resistive forces, indicating that the correct option for the work-energy problem is (c). The document also provides additional resources for learning about physics.
QA Work Energy and Power-3/ Work Energy Theorem
- 1. Physics Helpline L K Satapathy Work Energy Power 3 Work Energy Theorem 1Km G RW W K
- 2. Physics Helpline L K Satapathy Work Energy Power 3 Consider a drop of rain water , having mass 1 gram , falling from a height of 1 km as shown in the figure. It hits the ground with a speed of 50 m/s. Take ‘g’ as constant with a value of . The work done by (i) the gravitational force and (ii) the resistive force of air respectively are (a) (i) 1.25 J (ii) – 8.25 J (b) (i) 100 J (ii) 8.75 J (c) (i) 10 J (ii) – 8.75 J (d) (i) – 10 J (ii) – 8.25 J Question : 1Km 50m s 2 10 /m s
- 3. Physics Helpline L K Satapathy Work Energy Power 3 Answer : Work done by gravitational force : 2 3 10 10 10 ( )GW mgh N m J Ans Let work done by resistive force RW Gravitational force () = Weight of rain drop 3 2 2 10 10 10GF mg kg m s N Displacement () = 1 km 3 10S h m
- 4. Physics Helpline L K Satapathy Work Energy Power 3 Change in kinetic energy 2 21 1 0 2 2 K mv mv 3 21 2500 10 50 1.25 2 2000 K J 1.25 10 8.75 ( )R GW K W J Ans Correct option = (c) Initial KE = 0 & Final KE 21 2 mv Work energy theorem G RW W K
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