Question 1
In activity 15.5 the apparent weights of the floating objects A and B were both recorded as 0 N. Why?
The right answer is the one marked above.
The weight of the object is entirely balanced by the upthrust. The spring balance is left with no force to hold at all.
The mass has not changed and gravity still acts — otherwise there would be no weight to speak of. As the table shows, A weighs 1.1 N and the upthrust on it is 1.1 N as well.