Question

7. A car starts from rest and accelerates with 2 m/s2
for 10 seconds, After maintaining the velocity for
10 seconds, it comes to rest decelerating 1 m/s2
i) Draw the shape of V-t graph. ii) Find the maximum velocity attained and the total distance
travelled during the journey.

Answer 1

Maximum velocity attained is 20 metres/second
Total distance travelled is 500 metres

Initial speed (U) = 0
Acceleration (A) = 2
Time (T) = 10

Final speed (V) = U + AT
                         = 0 + 10 x 2
                         = 20

Hence maximum velocity attained is 20 m/s

Deceleration (D) = -1
Initial velocity after 20 seconds = V = 20
Final velocity (V1) = 0
Time (T1) = (V1 - U) / D
                = (0 - 20) / (-1)
                = 20 seconds

Total distance travelled = Distance while accelerating + Distance while decelerating + Distance without acceleration

= (0.5 x 2 x 10^2) + (20^2 / 2 x 1) + (20 x 10)
= 100 + 200 + 200
= 500 metres