From a stationary boat, the mass of which together with a person is 255 kg, an oar weighing 5 kg

| March 31, 2021 | education

From a stationary boat, the mass of which together with a person is 255 kg, an oar weighing 5 kg is thrown onto the shore with a horizontal speed relative to the ground of 10 m / s. How fast does the boat get?

We use the law of conservation of momentum. The total impulse of all bodies before interaction (throwing the oar) and after is the same. Momentum is calculated as the product of mass and velocity. Before the interaction, the momentum of the boat and the oar is zero, since the speed is zero. After interaction, the impulse of the oar is 5 kg X 10 m / s, the impulse of the boat (255 kg – 5 kg) X v, where v is the speed of the boat. You can make the equation: 50 kg m / s + 250 kg X v = 0, or 50 kg m / s = – 250 kg X v, whence v = – 0.2 m / s.



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