A man weighing 70 kg jumped from the shore into a stationary boat on the water at a speed of 6 m / s.
| April 18, 2021 | education
A man weighing 70 kg jumped from the shore into a stationary boat on the water at a speed of 6 m / s. At what speed will the boat move through the water with the person at the first moment after the person jumped, if the boat mass is 35 kg?
To find the speed of the indicated boat after a person jump, we apply the law of conservation of momentum: Vlch * (ml + mh) = mh * Vh, whence we express: Vlch = mh * Vh / (ml + mh).
Variables: mh – the mass of the person who jumped (mh = 70 kg); Vh – jump speed (Vh = 6 m / s); ml – boat weight (ml = 35 kg).
Calculation: Vlch = mh * Vh / (ml + mh) = 70 * 6 / (35 + 70) = 4 m / s.
Answer: At the first moment after the jump, the indicated boat will have a speed of 4 m / s.
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