Question

a car travelling at 36 km/h speed upto 72km/h in 5 seconds what is the acceleration?if the same car stops in20 seconds,find retardation(2m/s2 ; -1m/s2)​

Answer 1

Answer:

(2 m/(s^2)) & ( -1 m/(s^2))

Explanation:

Acceleration is change in velocity per unit time

the trick here is to first convert

(km/h) into (m/sec) because answer is in SI units and we have to give answer in SI units

so 36 km/h = 10 m/s

and 72 km/h = 20 m/s

change is 10m/s ( 20 - 10 )

time is 5 sec

so acceleration is 2 m/s^2 ( 10 / 5)

and similarly retardation is

change in velocity ( 0 - 20 )

as the car stops velocity is 0

time taken 20 sec

retardation is

(-20 / 20 )

-1 m/s^2