Final answer:
The area under the force curve on a force/time graph represents the impulse, which is the product of the force applied over a time interval, manifesting as a change in momentum.
Step-by-step explanation:
On a force/time graph, the quantity that is equal to the impulse is the area under the force curve between two time points. Impulse, represented by the symbol J, is defined as the product of a force applied to an object and the time interval over which that force is applied (F(t)Δt). This product results in a change in momentum or impulse. When the force is not constant, an average effective force (Feff) can be used to calculate the same impulse as the time-varying force. The area under the curve on such a graph has units of momentum and represents the impulse or change in momentum between the two points in time, t1 and t2.