Collision equation help needed please

How would I solve this?

This is kinda urgent as my exam is tomorrow morning

Hi @Sarah.Roycroft

a) Elastic potential energy is given by Ep=1/2kx^2 where k is the spring constant (250N/m) and x is compression (0.1m). For similar questions, x can be the extension if the spring is extended rather than compressed.

b) i) The sum of the momentum before they separate (zero) is equal to the sum of the momentum after the carts separate. The final momentum of the blue cart is given by p=mv = 2 x 0.5 = 1 kgms^-1 (let us assume that right is positive for this situation)
We therefore know that the momentum of the red cart must be -1 kgms^-1 (as both momentums must sum to zero).
Rearrange p=mv to find the velocity of the red cart (it should come out as negative).

b)ii) We have assumed no external forces, such as friction, are acting on the system.

Does that help?

yes that helped a little bit

@Sarah.Roycroft try the calculations and see if you get the right answer. If there’s something you’re still not sure of please let me know.

Best wishes for tomorrow

I got the right answer!! I got Vf (red) = -2.0m/s

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Brilliant, well done! I hope that knowledge serves you well tomorrow.