Question
Wed December 19, 2012 By: Ankush Sharma

A bird is flying in a straight line with velocity of |t-2| for 4 sec. Calculate the distance traveled by the bird? Answer is 4m.

Expert Reply
Wed December 19, 2012
 
v=|t-2|,as mod so always +ve
putting t=0,1,2,3,4 resp:
at t=0s, u=2m/s
at t=1s, u=1m/s
at t=2 s, u=0 m/s
at t=3s, u=1m/s
at t=4 s, u=2 m/s
so for first 2 s, it has uniform retardation:a=0-2/2=-1m/s2
for next 2 s it will have uniform acceleration:2-0/2=1m/s2
so for first 2 s distance travelled=s=ut+1/2 at2
so s=2x2-1/2 x1x2x2=2m
for next 2 s:
s=0x2+1/2 x 1x2x2=2m
so total distance travelled in 4 sec=2+2=4 m
 
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