Kinematics Question 381

Question: A truck has to carry a load in the shortest time from one station to another station situated at a distance L from the first. It can start up or slowdown at the same acceleration or deceleration what maximum velocity must the truck attain to satisfy this condition?

Options:

A) La

B) 2La

C) 3La

D) 5La

Show Answer

Answer:

Correct Answer: A

Solution:

Let v be the maximum velocity attained and t the total time of journey. t’ it’s the duration of acceleration and retardation. Then v=0+at.
L=12at2+v(t2t)+12at2

=a(va)2+v(t2va)

=v2a+vt2v2a=vtv2a

=t=Lv+vadvdt=0 vmax=La



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