Abox is moved 10 m across a smooth floor by a force f making a downward angle with the floor, so that there is effectively a 4 n force acting parallel to the floor in the direction of motion and a 3 n force acting perpendicular to the floor. the force f acts for 20 seconds. the impulse delivered to the box by the floor during this process has magnitude
a- 80 ns
b- 60 ns
c- 100 ns
d- zero
e- can't tell without know the mass of the box