Question

(iv) average velocity of aeroplane in km/h
2. A particle moves on a straight line in such way that it covers 1st half distance with speed 3 m/s and ne
half distance in 2 equal time intervals with speeds 4.5 m/s and 7.5 m/s respectively. Find average speed
of the particle.
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Answer 1

Explanation:

Suppose total distance is 2x

 then first half is 2x traveled with 3m/s so time taken t1=32x

after it suppose it take 2t time then 

its half i.e. t with 4.5m/s so distance s1=4.5t

another half i.e. t with 7.5m/s so distance s2=7.5t

this distance s1+s2=2x or 4.5t+7.5t=12t=2x or x=6t

Average speed is v=timedistance=t1+2t4x=32x+2t4x putting x=6t we get v=4m/s