Final answer:
The velocity of the cart when it reaches the wall will still be 2 m/s if there are no external forces other than the collision. The final velocity after impact depends on whether the collision is elastic or inelastic and may involve complex calculations considering momentum and energy conservation.
Step-by-step explanation:
If a cart with no fans starts with a velocity of 2 m/s and is moving towards a wall, the velocity of the cart when it reaches the wall will still be 2 m/s assuming there is no acceleration involved such as friction or air resistance. However, once it strikes the wall, it will either come to a stop (0 m/s) if the collision is perfectly inelastic or it will rebound with some velocity in the opposite direction if the collision is elastic.
In the physics problems described, where objects collide with walls or each other, it is essential to consider the conservation of momentum and energy when trying to calculate final velocities. For instance, in an elastic collision, both kinetic energy and momentum are conserved, while in a perfectly inelastic collision, only momentum is conserved. The change in velocity will depend on the specific situation, such as the mass of the objects and their initial velocities.