Question

Question #dea10

Answer 1

Considering rectilinear motion of the body with initial velocity `u` and uniform acceleration `a`

As the body travels `1.8m` in first 3sec

`1.8=u*3+1/2*a*3^2`
`=>0.6=u+1.5a.....[1]`

As the body travels `4m` in first 8sec

`1.8+2.2=4=u*8+1/2*a*8^2`

`=>0.5=u+4a.......[2]`

Subtracting [1] from[2]

`2.5a=0.5-0.6=-0.1`

`=>a=-0.04ms^-2`

Inserting `a=-0.04` in [2]

`0.5=u-4*(0.04)`

`=>u=0.66ms^-1`

velocity at the end of 9 sec
using equation `v=u+at`

`v=0.66-0.04*9=0.66-0.36=0.3ms^-1`