Question

Физика, ГИА.Тележка массой 20 кг движется со скоростью 0,8 м/с, сцепляется с другой тележкой массой 30 кг, движущейся ей навстречу. После сцепки начали двигаться со скоростью 0,2 м/с в направлении движения первой тележки. Чему равна скорость движения второй тележки до сцепки?

Answer 1

Дано:                   решение
m1=20 кг             по з.сохр.импульса 
v1= 0,8 м/c          m1v1+m2v2= m1 v1(конечн.) + m2v2(конечн.); 
m2= 30 кг            m1v1-m2v2=m общ* v общ;(т.к двигались в сцепке);(минус,т.к 
Vобщ=0,2м/c                                                               двигались навстречу);    
найти: v2             m2v2=m1v1 - (m общ * v общ);
                          v2= (m1v1-(m общ* v общ)) / m2;
                          v2= (20*0,8-(50 кг * 0,2 ) / 30 кг= 0,2 м/c 
(Единицы изм.добавишь)

Answer 2

Calculation of the Velocity of the Second Cart before the Collision

To determine the velocity of the second cart before the collision, we can use the principle of conservation of momentum. According to this principle, the total momentum before the collision is equal to the total momentum after the collision.

The momentum of an object is given by the product of its mass and velocity. Therefore, we can calculate the momentum of the first cart before the collision as the product of its mass (20 kg) and velocity (0.8 m/s):

Momentum of the first cart before the collision = mass of the first cart × velocity of the first cart = 20 kg × 0.8 m/s = 16 kg·m/s

Similarly, we can calculate the momentum of the second cart before the collision as the product of its mass (30 kg) and velocity (unknown):

Momentum of the second cart before the collision = mass of the second cart × velocity of the second cart = 30 kg × velocity of the second cart

Since the two carts are moving towards each other, their velocities have opposite directions. Therefore, we can consider the velocity of the second cart as negative.

According to the conservation of momentum, the total momentum before the collision is equal to the total momentum after the collision. Therefore, we can write the equation:

Momentum of the first cart before the collision + Momentum of the second cart before the collision = Momentum of the first cart after the collision + Momentum of the second cart after the collision

Substituting the known values, we have:

16 kg·m/s + 30 kg × velocity of the second cart = (20 kg + 30 kg) × 0.2 m/s

Simplifying the equation, we can solve for the velocity of the second cart:

16 kg·m/s + 30 kg × velocity of the second cart = 50 kg × 0.2 m/s

30 kg × velocity of the second cart = 50 kg × 0.2 m/s - 16 kg·m/s

velocity of the second cart = (50 kg × 0.2 m/s - 16 kg·m/s) / 30 kg

Using the given values and performing the calculation, we find:

velocity of the second cart = (10 kg·m/s - 16 kg·m/s) / 30 kg = -6 kg·m/s / 30 kg = -0.2 m/s

Therefore, the velocity of the second cart before the collision is -0.2 m/s.