Physics · GRAVITATION

Four point masses, each of mass \( m \), are fixed at the corners of a square of side \( l \). What is the minimum work required to slowly move an additional test mass \( m_0 \) from infinity to the center of the square?

1. A
   \( 4\sqrt{2} \frac{G m m_0}{l} \)
2. B
   \( 2\sqrt{2} \frac{G m m_0}{l} \)
3. C
   \( -4\sqrt{2} \frac{G m m_0}{l} \)
4. D
   \( -2\sqrt{2} \frac{G m m_0}{l} \)