What does the area under a speed-time graph represent

It represents the whole distance traveled. Hope this helps!

Explanation:

the force required to move the cart is divided by three or 33.33 n.

here we know that ball will drop down by total distance 3.2 m

so here we know that

now using kinematics

now in the same time it will cover horizontal distance of 0.75 m

so speed of the ball will be