Answer:
The speed of the object is 20.24 m/s. 
Step-by-step explanation:
For a body of mass 'm' travelling with velocity 'v' , its kinetic energy is gievn by - 
 --- 1
The momentum of body is given by - 
 ---- 2
Dividing equation 1 and 2 , we get - 

Given that ,
KE = 249 J
p = 24.6 kg.m/s
Substituting the 2 values in the above equation , we get - 
v = 20.24 m/s.