1.

A bullet fired into a fixed target loses 20% of its K.E.in penetrating 1 cm. Find the total distance penetrated by bullet before it comes to rest :

Answer»

2 cm
3 cm
4 cm
5 cm

Solution :Here `1/2mv^2=(1-(20)/(100))xx1/2"mu"^2`
or`v^2=4/5u^2`
APPLYING `v^2-u^2=2aS,4//5u^2=u^2-2axx1` or `a=(u^2)/(10)`.
LET .X. be the distance penetrated.When bullet comes to rest i.e v=0, then `:. 0=u^2-2(u^2/10)x`
or x=5 cm.


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