Question

ДаМ 20 БаЛоВчеловек массой 60 кг прыгнул на берег из неподвижной лодки на воде со скоростью 4 м/с. с какой скоростью станет двигаться по воде лодка после прыжка человека, если масса лодки 40 кг

Answer 1

30м/c cтанет двигаться лодка

Answer 2

To answer your question, we can use the principle of conservation of momentum. According to this principle, the total momentum before the jump is equal to the total momentum after the jump.

Initial Momentum:

The initial momentum of the system (person + boat) can be calculated by multiplying the mass of the person by their initial velocity and adding it to the mass of the boat multiplied by its initial velocity. In this case, the person's mass is 60 kg and their initial velocity is 4 m/s, while the boat's mass is 40 kg and its initial velocity is 0 m/s (since it is stationary). Therefore, the initial momentum is:

(60 kg * 4 m/s) + (40 kg * 0 m/s) = 240 kg·m/s

Final Momentum:

After the person jumps onto the shore, they will come to rest on the shore. This means their final velocity is 0 m/s. The boat, on the other hand, will start moving in the opposite direction with a certain velocity. Let's call this velocity V.

The final momentum of the system can be calculated by multiplying the mass of the person by their final velocity (which is 0 m/s) and adding it to the mass of the boat multiplied by its final velocity (which is V). Therefore, the final momentum is:

(60 kg * 0 m/s) + (40 kg * V) = 40 kg * V

Conservation of Momentum:

According to the principle of conservation of momentum, the initial momentum is equal to the final momentum. Therefore, we can equate the two expressions for momentum:

240 kg·m/s = 40 kg * V

Solving for V:

To find the final velocity of the boat, we can rearrange the equation and solve for V:

V = (240 kg·m/s) / 40 kg

V = 6 m/s

Answer:

Therefore, the boat will start moving in the opposite direction with a velocity of 6 m/s after the person jumps onto the shore.

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