A bullet of mass 10 g is fired horizontally with a velocity 1000 $ms^{- 1}$ from a rifle situated at a height 50 m above the ground. If the bullet reaches the ground with a velocity 500 $ms^{- 1}$,the work done against air resistance in the trajectory of the bullet is (g=$10ms^{- 2})$

Question

Dr. Abubacker · Accepted Answer

(c) From equation of motion,
$v^{2} = u^{2} - 2as$
$(500)^{2} = (1000)^{2} - 2 	imes a 	imes s$
$s = \frac{(1000)^{2} - (500)^{2}}{2a} = \frac{375000}{a}$
$	herefore$work done against air resistance
$w = Fs$
$= ma 	imes s$
$= \frac{10}{1000}a 	imes \frac{375000}{a}$
$= 3750\ J$

Q. A bullet of mass 10 g is fired horizontally with a velocity 1000 $ms^{- 1}$ from a rifle situated at a height 50 m above the ground. If the bullet reaches the ground with a velocity 500 $ms^{- 1}$,the work done against air resistance in the trajectory of the bullet is (g=$10ms^{- 2})$

Explanation

Reviewed by Dr. Abubacker

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