An object of mass 2kg collides with an object of mass 1kg that is at rest, as shown in the figure. A graph of the force as a function of time that the 1kg object exerts on the 2kg object is shown. After the collision, the 2kg object has a speed of 2m/s, and the 1kg object has a speed of 8m/s. A student must determine the initial speed v0 of the 2kg object. Which of the following options shows the correct substitutions into the equation ?p-->p? =F?F--> ?t so that the initial speed of the unknown object can be determined?

a) (2?kg)(2?ms?v0)=(8000?N)(0.00125?s), because the maximum force exerted on the 2kg object must be considered.

b) (2?kg)(2?ms?v0)=12(8000?N)(0.00125?s), because the average force exerted on the 2kg object must be considered.

c) (2?kg?1?kg)(2?ms?v0)=(8000?N)(0.00125?s), because the difference in mass and the maximum force exerted on the 2kg object must be considered.

d) (2?kg?1?kg)(2?m/s?v0)=12(8000?N)(0.00125?s), because the difference in mass and the average force exerted on the 2kg object must be considered.