It makes no difference whether there are two bulbs or 1000 bulbs. If they are all in series then when one bulb burns out, or one little piece of wire between two bulbs comes loose, ALL of them go dark. In that situation it's a challenge to find where the break in the circuit is because all of the bulbs are dark.
ANSWER:
a) 25.97 N
b) 47.53 N
STEP-BY-STEP EXPLANATION:
Given:
Beaker mass = 1.2 kg
Water mass = 2.5 kg
Water density = 1000 kg/m^3
Block mass = 3.8 kg
Block density = 3300 kg/m^3
a)
The first thing is to calculate the volume of the block, like this:
Mass of water displaced by the block is:
The block will receive a push from the water equal to the weight of the water displaced by the block, or the effective weight of the block will be reduced by the same amount:
Therefore, 25.97 N is the reading on the hanging scale.
b)
The bottom scale will gain by the same amount (1.15 kg). Therefore, the totalweight on the bottom scale is:
Therefore, 47.53 N is the reading on the lower scale.