To calculate the final velocity, we use Newton's first equation of linear motion:v=u+at
Where v is final velocity
u is initial velocity
a is the average acceleration
t is the time taken during acceleration.
Therefore,
v=0+2.5m/s²*6.00s
=15m/s
Decelerating from 15m/s;
v=15m/s+(-2m/s²×4.0s)
=3m/s
To get the distance it travelled, we use
v²=u²+2as
During acceleration, the distance travelled is calculated as below.
15²=0+2×2.5S
225=5S
S=45meters
During decellaration, displacement is calculated as below,
3²=15²+(2×4S)
9=225+8S
8S=216
S=27meters
Total displacement=45m+27m
=72 meters.
