An oar pushes water towards the back of a boat. A pupil says that the water does not push on the oar because the oar is pushing the water. Which correction is needed?
The water exerts an equal force backwards on the oar, in the same direction.
The water exerts an equal force forwards on the boat, not on the oar.
The water exerts an equal force forwards on the oar, in the opposite direction.
The water exerts a smaller force forwards on the oar, in the opposite direction.