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 .
What is the Investigation about!
While the answer is that it does, it transmits light VERY poorly. Most of the light bounces off it and the rest is refracted into the ocean. This is why you can't see much that is far away from you in the ocean unlike if you're just on land.
Answer:
work done would be I don't know