A ferry boat loaded with rocks has to pass under a bridge. The maximum height of the rocks is slightly more than the height of the bridge so that the boat just fails to pass under the bridge. Should some of the rocks be removed or some more rocks be added?
Answers
Ferry boat has to pass under the bridge. Okay !!!
If we will remove the rocks, then upthrust will decreases due to the decrease in mass of the ferry boat loaded with stones.
As a result of which it will come little up. Now, there will be problem. At first only, the height of the boat with stone is more than the height of the bridge.
If we will remove, then also, it raise up and still height of boat will be greater than bridge. As a result it cannot pass.
Now, On the other hand, If we will increase the mass of the boat by keeping the stone more on it, then its Upthrust increases. As a result of which, it will move little down which will make it easier to move under the bridge without affecting its height.
Hope it helps.
Answer:Sometimes rocks has to be removed.
Explanation: Volume of boat is larger than the volume of a single rock.
So when we will remove a rock, BOAT WILL COME UP( To be balanced by the buoyant force , as it has to float in water so net force in vertical direction must be zero)
So volume of boat inside water will decrease (compared to the initial) and level of water will fall.
BUT,
Due to the rock which you removed out of boat and dropped in water.... Level of water will increase a bit but NOT EQUAL TO THE VERY INITIAL LEVEL OF WATER.
Because VOLUME of ROCK is less than the volume of boat (so displaced volume of water by rock will also be less than the volume displaced by boat).
SO THERE WILL BE AN FINAL DECREASE IN THE LEVEL OF WATER WITH RESPECT TO THE INITIAL LEVEL.
SO BOAT WILL PASS EASILY.