Question

Мальчик на коньках массой 40 кг, стоя на катке, бросает груз массой 2 кг под углом 60 градусов к горизонту со скоростью 10 м/c. Какую скорость приобретет мальчик?

Answer 1

Закон сохранения импульса
M*u = m*v0*cos(60), где
M -- масса мальчика
m -- масса груза
u -- скорость мальчика
v0 -- скорость груза
Отсюда u = (m/M) * v0 * cos(60) = 0.4 м/c 

Answer 2

Calculation of the Boy's Final Velocity

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

The momentum of an object is given by the product of its mass and velocity. Therefore, the momentum of the boy before the throw is given by:

Momentum before = mass of the boy × velocity of the boy

The momentum of the thrown object is given by:

Momentum of the object = mass of the object × velocity of the object

Since the total momentum before and after the throw is the same, we can write:

Momentum before = Momentum of the object

Let's calculate the momentum before the throw:

Momentum before = mass of the boy × velocity of the boy

Given: - Mass of the boy = 40 kg - Velocity of the boy = 10 m/s

Momentum before = 40 kg × 10 m/s

Now, let's calculate the momentum of the object:

Momentum of the object = mass of the object × velocity of the object

Given: - Mass of the object = 2 kg - Angle of throw = 60 degrees - Velocity of the object = 10 m/s

To calculate the horizontal component of the velocity of the object, we can use the formula:

Horizontal velocity = velocity of the object × cos(angle of throw)

To calculate the vertical component of the velocity of the object, we can use the formula:

Vertical velocity = velocity of the object × sin(angle of throw)

Let's calculate the horizontal and vertical components of the velocity of the object:

Horizontal velocity = 10 m/s × cos(60 degrees)

Vertical velocity = 10 m/s × sin(60 degrees)

Now, let's calculate the momentum of the object:

Momentum of the object = mass of the object × horizontal velocity

Given: - Mass of the object = 2 kg - Horizontal velocity = 10 m/s × cos(60 degrees)

Momentum of the object = 2 kg × (10 m/s × cos(60 degrees))

Now that we have calculated the momentum before and the momentum of the object, we can equate them to find the final velocity of the boy.

Momentum before = Momentum of the object

Mass of the boy × velocity of the boy = 2 kg × (10 m/s × cos(60 degrees))

Simplifying the equation:

40 kg × 10 m/s = 2 kg × (10 m/s × cos(60 degrees))

Now, let's solve the equation to find the final velocity of the boy.