1.

The speed of a car was `50 km//hr` for the first 900s, then 40 km/hr for the 50 km and then the car decelerated uniformly at `10 km//hr^(2)` till it came to rest. The average speed of the car was :A. 50 km/hrB. 7.2 m/sC. 30 km/hrD. 9.0 m/s

Answer» Correct Answer - B
Av. Speed `= ("Total distance")/("Total time")`
`= ((v_(1)t_(1) + v_(2) t_(2) + (v_(2)^(2))/(2a_(2)))/(t_(1) + t_(2) + (v_(2))/(a_(2))))`


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