A person weighing 80 kg moves from bow to stern in a boat 5 m long. What is the mass of the boat
| February 24, 2021 | education
A person weighing 80 kg moves from bow to stern in a boat 5 m long. What is the mass of the boat if during this transition it has moved 2 m in still water in the opposite direction?
These tasks: mh (mass of a person walking on the boat) = 80 kg; L (length of the indicated boat) = 5 m; S (boat movement) = 2 m.
To find the mass of the boat, it is necessary to use the formula: (mh + ml) * Vl = mh * Vh (the law of conservation of momentum is used).
(mh + ml) * S / t = mh * L / t.
(mh + ml) * S = mh * L.
ml * S = mh * L – mh * S.
ml = (mh * L – mh * S) / S.
Let’s calculate: ml = (80 * 5 – 80 * 2) / 2 = 240/2 = 120 kg.
Answer: The boat, according to the calculation, has a mass of 120 kg.
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