Which of the following best defines the impulse delivered to a system during a time interval Δt?
a) Half the product of the system’s mass and its change in velocity, treated as a vector quantity.
b) The product of the net external force acting on the system and the time interval, treated as a vector pointing in the direction of the force.
c) The product of the net external force acting on the system and the time interval, treated as a scalar quantity.
d) The product of the system’s mass and its speed, treated as a scalar quantity.