Question

An object moves with a uniform speed of 10m/s for 5seconds and then with a uniform speed of 5m/s for 10s.find its average speed

Answer 1

at first , 
10m/s for 5sec 
 s= vt 
   = 10* 5
    = 50 m
in second , 
  5m/s for 10 sec
s= vt 
  = 5*10 
  = 50 m 
totak distance = 50 +50 
                      = 100 m 
total time = 10 +5 
               = 15 sec 
average velocity = total distance / total time taken 
                          = 100/ 15
                           =6.66 m/s