Answer:
Let d be the density of fluid.
So , Initial reading of balance, F1 =30dg N
After the level reaches 50cm^3
Final reading of balance , F2 =50dg N
Given that difference between final and initial reading is 30g
i.e, F2 −F1
=30 g
⟹50dg−30dg=30g
⟹20dg=30g
⟹d=30g/20g
⟹d=1.5g/cm^3
So, density of fluid is 1.5g/cm^3
<span>The fluid in a graduated cylinder should be read at the BOTTOM of the meniscus.</span>
The height of the roof is <u>3.57m</u>
Let the drops fall at a rate of 1 drop per t seconds. The first drop takes 5t seconds to reach the ground. The second drop takes 4t seconds to reach the bottom of the 1.00 m window, while the 3rd drop takes 3t s to reach the top of the window.
Calculate the distances traveled by the second and the third drops s₂ and s₃, which start from rest from the roof of the building.

The length of the window s is given by,

The first drop is at the bottom and it takes 5t seconds to reach down.
The height of the roof h is the distance traveled by the first drop and is given by,

the height of the roof is 3.57 m
Take into account that density and relative density are given by:

Take into account that the volume associated to each of the given sustances in the table is determined by the Level Difference (because it is the change in the volume of the water of the recipient in which the substance is immersed).
The density of water in kg/m^3 is 1000 kg/m^3.
Due to the density must be given in kg/m^3, it is necessary to express the volumes of the table in m^3 and mass in kg, then, consider the following conversion factor:
1 m^3 = 1000000 ml
1 kg = 1000 g
Then, you obtain the following results:
Brass:

Cooper: