Question

Мальчик массой 30 кг,стоя на коньках горизонтально бросил камень массой 1 кг начальная скорость камня 3м/с. найти скорость мальчика после броска

Answer 1

Задача на закон сохранения импульса

Answer 2

Calculation of the Boy's Velocity After Throwing the Stone

To calculate the velocity of the boy after throwing the stone, we can use the principle of conservation of momentum. According to this principle, the total momentum before the stone is thrown is equal to the total momentum after the stone is thrown.

The momentum of an object is given by the product of its mass and velocity. Therefore, we can write the equation:

Initial momentum = Final momentum

The initial momentum of the system (boy + stone) is the product of the boy's mass and his initial velocity, which is zero since he is standing still on skates:

Initial momentum = (mass of the boy) * (initial velocity of the boy)

The final momentum of the system is the sum of the momentum of the boy and the momentum of the stone. The momentum of the stone is the product of its mass and its final velocity:

Final momentum = (mass of the boy) * (final velocity of the boy) + (mass of the stone) * (final velocity of the stone)

Since the stone is thrown horizontally, its final velocity is the same as its initial velocity, which is 3 m/s.

Now we can set up the equation:

(mass of the boy) * (initial velocity of the boy) = (mass of the boy) * (final velocity of the boy) + (mass of the stone) * (final velocity of the stone)

Substituting the given values: - Mass of the boy = 30 kg - Mass of the stone = 1 kg - Initial velocity of the boy = 0 m/s - Final velocity of the stone = 3 m/s

We can solve for the final velocity of the boy.

Calculation:

(30 kg) * (0 m/s) = (30 kg) * (final velocity of the boy) + (1 kg) * (3 m/s)

Simplifying the equation:

0 = (30 kg) * (final velocity of the boy) + (1 kg) * (3 m/s)

0 = 30 kg * (final velocity of the boy) + 3 kg m/s

To isolate the final velocity of the boy, we can rearrange the equation:

(30 kg) * (final velocity of the boy) = -3 kg m/s

final velocity of the boy = (-3 kg m/s) / (30 kg)

final velocity of the boy = -0.1 m/s

Therefore, the final velocity of the boy after throwing the stone is -0.1 m/s. The negative sign indicates that the boy is moving in the opposite direction to the thrown stone.

Please note that the negative sign indicates the direction of the velocity, not the speed. The speed of the boy after throwing the stone is 0.1 m/s.