A bullet of mass 10g leaves a rifle at an initial velocity 1000 m/s and strikes earth at the same level with a velocity of 500 m/s. The work in overcoming the resistance of air will be:
Correct answer: C. 3750 J
- A. 500 J
- B. 5000 J
- C. 3750 J
- D. 475 J
Explanation
work energy theorem Work done in overcoming the air resistance=Loss in energyInitial KE = 0.5x m x v1^2 = 0.5 x 0.01 x 10^6 = 5000 J Final KE = 0.5 x m x v2^2 = 0.5 x 0.01 x 25 x 10^4 = 1250 J Work done in overcoming the resistance = 5000-1250 Work done = 3750 J Mathematically option A , B & D are incorrect
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About Work-Energy Theorem
The work-energy theorem states that the net work done on an object equals its change in kinetic energy. Questions involve positive and negative work, variable forces and force-displacement graphs, acceleration or deceleration, and the difference between this theorem and conservation of mechanical energy, which also requires attention to potential energy and non-conservative work.
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