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:
[tex]\begin{gathered} d=\frac{m}{V} \\ V=\frac{m}{d} \\ \text{ we replacing} \\ V=\frac{3.8}{3300} \\ V=0.00115m^3 \end{gathered}[/tex]Mass of water displaced by the block is:
[tex]\begin{gathered} d=\frac{m}{V} \\ m=d\cdot V \\ m=1000\cdot0.00115 \\ m=1.15kg \end{gathered}[/tex]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:
[tex]\begin{gathered} W=(m_b-m)\cdot g \\ \text{ we replacing} \\ W=(3.8-1.15)\cdot9.8 \\ W=25.97\text{ N} \end{gathered}[/tex]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:
[tex]\begin{gathered} W=(1.2+2.5+1.15)\cdot9.8 \\ W=4.85\cdot9.8 \\ W=47.53\text{ N} \end{gathered}[/tex]Therefore, 47.53 N is the reading on the lower scale.
