Question

Мальчик массой 50 кг спрыгнул с неподвижной лодки массой 100 кг, расположенной в воде около берега. с какой скоростью отъехала лодка от берега, если скорость мальчика направлена горизонтально и равна 1 м/с?

Answer 1

Дано,
1-мальчик
2-лодка
m1 =50 кг
m2=100 кг
v1 = 1 м/с
найти
v2
решение
закон сохранения импульса
m1v1 = m2v2 
v2 = v1 * m1/m2 = 1 * 50/100 = 0,5 м/с
ответ
v2 = 0,5 м/с

Answer 2

Calculation of the Boat's Speed

To calculate the speed at which the boat moves away from the shore when a boy weighing 50 kg jumps off a stationary boat weighing 100 kg, 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.

The momentum of an object is calculated by multiplying its mass by its velocity. In this case, the momentum of the boy and the boat before the jump is zero because they are both stationary. After the jump, the momentum of the boy and the boat combined is still zero because the system is isolated and no external forces act on it.

Let's assume the velocity at which the boat moves away from the shore is v m/s. The momentum of the boy is given by the product of his mass (50 kg) and his velocity (1 m/s), which is 50 kg*m/s. The momentum of the boat is given by the product of its mass (100 kg) and its velocity (v m/s), which is 100v kg*m/s.

According to the principle of conservation of momentum, the sum of the initial momenta (0 kg*m/s) is equal to the sum of the final momenta (50 kg*m/s + 100v kg*m/s). Therefore, we can write the equation:

0 kg*m/s = 50 kg*m/s + 100v kg*m/s

Simplifying the equation, we get:

50 kg*m/s = 100v kg*m/s

Dividing both sides of the equation by 100 kg*m/s, we find:

v = 0.5 m/s

Therefore, the boat moves away from the shore with a speed of 0.5 m/s.

Please note that the above calculation assumes an idealized scenario without considering factors such as friction, air resistance, and water resistance. In reality, these factors would affect the actual speed at which the boat moves away from the shore.