Final answer:
When mass m1 is at rest, the tension in the string is equal to the weight of block m1, because the net force on m1 must be zero.
Step-by-step explanation:
If mass m1 remains at rest, then the value of tension in the string is equal to the weight of block m1. This can be shown by using Newton's second law, which states that if an object is at rest, the net force acting on it is zero. Since block m1 is at rest, and assuming it is hanging and connected to a second block through an ideal pulley system, the tension in the string (T) supporting m1 would be exactly balanced by the weight of that block (m1g), so T = m1g. Therefore, the tension in the string would be the same as the weight of block m1, which in this case is the product of its mass (4 kg) and the acceleration due to gravity (g, approximately 9.8 m/s2). The acceleration of block m1 is zero since it is stated that the block remains at rest. Likewise, the normal force on block m1 is irrelevant in this context since that force acts perpendicular to a surface, and there is no surface mentioned for m1 in the rest condition.