MediumPhysicswork done
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An object of mass 5 kg falls from rest through a vertical distance of 20 m and reaches a velocity of 10 m/s. How much magnitude of work is done by the push of the air on the object ? (g = 10 m/s²).
A
350 J
B
750 J
C
200 J
D
300 J
Explanation
Work-energy: Wg + Wair = ΔK mgh + Wair = ½mv² 5×10×20 + Wair = ½×5×100 1000 + Wair = 250 ⇒ Wair = −750 J Magnitude = 750 J
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