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## Answers

Initial Velocity (u) = 72 km/hr = 72 * 1000 m/3600 s = 72*5/18m/s = 20 m/s

Final Velocity (v)= 0

time = 10 sec

we know that ,

v = u +at

0 = 20 +a*10

-20 /10 = a

or a= -2 m/s²

Hope this helps you!

Thank You!!

Note :-

**1k**

**m = 1000 m**

**and 1 hr = 60 minutes**

**and 1 min = 60 seconds**

**therefore , 1 hr = 60 *60 sec = 3600 seconds**

and hence

**1 km / hr =**1000 m / 3600 s =

**5/18 m/s**

Just Remenber two Shortcuts :

**km/hr = 5/18 m/s**

**and 1 m/s = 18/5 km/hr**

final velocity=0

v=u+at

0= 20+a*10

0=20+10a

-20/10=a

a=-2 m/s²