A particle moving along a straight line with a constant acceleration of `-4 m//s^2` passes through a point `A` on the line with a velocity of `+ 8 m//s` at some moment. Find the distance travelled by the particle in `5` seconds after that moment.

Options

A. 26 m
B. 8 m
C. 18 m
D. 10 m

Answer

A

Explanation

`u=+8 m//s`
`a=-4 m//s_(2)`
`v=0`
`rArr 0=8-4t` or `t=2 sec`
displacement first `2 sec`
`S_(1)=8 xx 2 +(1)/(2)(-4)2_(2)=8m`
displacement in next `3 sec`
`S_(2)=0 xx 3+(1)/(2)(-4)3_(2)=-18 m`
distance travelled `= |S_(1)|+|S_(2)|=26 m`
Ans `26 m`
Alter

total distance `= (1)/(2) xx 2 xx 8 +(1)/(2) xx 3 xx 12`
`= 8 + 18 = 26 m`.