Question

If the $10\text{kg}$ and $20\text{kg}$ bodies are considered to be system $1$ and $30\text{kg}$ body is considered as system $2$ , how many forces would appear to be acting as external forces for system $1$?

• A. $1$
• B. $2$
• C. $3$
• D. $4$

Answer 1

The correct option is C $3$

Drawing FBD of system 1

The tension in the rope between 10 kg and 20 kg is internal to the system and therefore not shown in FBD.