Question 5
In activity 01 the pull on the block is increased gradually and the Newton balance is read at the instant the block just begins to move. What does that reading give?
The right answer is the one marked above.
The limiting friction between the block and the table. The force needed to just start the motion is equal to the maximum friction those surfaces can produce.
The balance is pulled horizontally, so it can say nothing directly about the weight or the normal reaction — those are the vertical forces.