A motor car moving with a uniform speed of 20 ms−1 comes to rest on the application of brakes after travelling a distance of 10 m. Its acceleration is
20m/sec2
−20m/sec2
−40m/sec2
+2m/sec2
Using, v2=u2+2aS
⇒o=u2+2aS
⇒a=−u22S
a=−(20)22×10
a=−20ms−2
a car travels with a uniform velocity of 20m/s for 5 seconds.the brakes are applied and the car is uniformly retarted.it comes to rest in further 8seconds.calculatethe distance travelled before the brakes are applied and the distance covered after the brakes are applied.find its average speed