Question

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.
A. `10`
B. `26`
C. `13`
D. `20`

Answer 1

Correct Answer - B
u=+8 m/s
a=-4 m`//s^(2)`
v=0
`rArr 0=8-4t` or `t=2sec`
displacement in first 2 sec.
`S_(1)=8xx2+1/2.(-4).2^(2)=8 m`
displacement in next 3 sec.
`S_(2)=0xx3+1/2 (-4) 3^(2) =-16 m`
Distance travelled `=|S_(1)|+|S_(2)|=26 m`
Aliter

total distance `1/2xx2xx8+1/2xx3xx12=8+18=26m`