Question

A PERSON AT REST STARTS

Answer 1

Given :  Total time  taken  T=10 s                      u=0  m/s

Let the time taken during 1st half and second half be  t1  and  t2  respectively.

∴  T=t1+T2         ⟹t2=10−t1

Let the acceleration of the person during 1st half be  a.

For 1st half :     S=ut+21at2

∴   50=0+21at12    ⟹a=t12100(1)

Also    V12−02=2a(50)     ⟹V12=100a (2)

2nd half :     50=V1t2=V1(10−t2)

⟹     V1=10−t150(3)

Using (1) and (3) in (2)   we get(10−t1)2(50)2=100×t12100

OR       10−t1t1=2                 ⟹t1=320  s

From (3),        V1=10−32050=15