Question

suppose that there are two objects next to each other, object at the right is A, object at the left is B.now we have these situations:
1) we push object A to the left side
2) we pull object B to the left side(in this case they're stuck to each other)
Do the forces that B exert on A have the same magnitude and direction in both situations?

Answer 1

Task:

Suppose that there are two objects next to each other, object at the right is A, object at the left is B. Now we have these situations:

1) we push object A to the left side

2) we pull object B to the left side (in this case they're stuck to each other)

Do the forces that B exert on A have the same magnitude and direction in both situations?

Solution:

1)

2)

1) $m_A a = F - P_{BA} - F_{Afr} = F - P_{BA} - \mu_A m_A g$

$$P_{BA} = F - m_A a - \mu_A m_A g = F - m_A (a + \mu_A g)$$

2) $m_A a = P_{BA} - F_{Afr} = P_{BA} - \mu_A m_A g$

$$P_{BA} = m_A a + \mu_A m_A g = m_A (a + \mu_A g)$$

**Answer:**

The forces that B exert on A have different magnitudes and directions in different situations