Question

starting from A stationary position Rahul Paddles his bicycle to attend a velocity of 6 m per second in 30 seconds then he apply brakes such that the velocity of a bicycle comes down to 4 m per second in the next 5 seconds. calculate the acceleration of the bicycle in both the cases

Answer 1

when he start cycling.
v=6m/s
u=0m/s
time=30sec
$a = \frac{v - u}{t} \\ a = \frac{6 - 0}{30} \\ a = \frac{6}{30} \\ a = 0.2$
when he applied brakes during cycling.
v=0m/s
u=4m/s
time=5sec
here acceleration=retardation
$r = \frac{v - u}{t} \\ r = \frac{0 - 4}{5} \\ r = \frac{ - 4}{5} \\ r = - 0.8ans$
retardation always positive.