When the tin can is pushed into the water keeping its mouth upwards, it displaces more volume of water, and, therefore, it experiences more upthrust. But when it is pushed into the water with its mouth towards water, it displaces less volume of water (as water enters it). As a result, the upthrust is also less. Thus, it is comparatively easier to push a tin can into water with its mouth towards water than away from it.
Explain why is it difficult to push a tin can into water keeping its mouth upwards than when its mouth is kept downwards towards the water