A loaded grocery cart of mass 5.25kg is rolling across a parking lot in a strong wind.you apply a force F=(30N)i-(40N)j to bring it to rest after a displacement s=(-9.0m)i-(3.0)j.
a)Determine the velocity of the cart before you applied the force.
b)Assume that the force was applied on a string which compressed against a frictional force of 6.7N.What is the spring constant given that the spring compressed by 450cm.