Answer:
The speed of the cart and clay after the collision is 50 cm/s .
Explanation:
Given :
Mass of lump , m = 500 g = 0.5 kg .
Velocity of lump , v = 30 cm/s .
Mass of cart , M = 1 kg .
Velocity of cart , V = 60 cm/s .
We know by conservation of momentum :

Here ,
is the speed of the cart and clay after the collision .
Putting all value in above equation .
We get :

Hence , this is the required solution .