K.C.S.E Physics Q & A - MODEL 2011PP1QN019

K.C.S.E Physics Q & A - MODEL 2011PP1QN019

​(a) State the condition necessary for a body to float in a fluid. 
(b) A ship made of steel is observed to float on water yet the density of steel is approximately eight times that of water. Explain this observation. 
(c) Figure 17 shows three stages of an experiment to determine relative density of cork which normally floats on water. To make it sink, a sinker is hung below the cork.

​In (1) a spring balance is used to measure the weight W of the cork in air.
In (II) the spring balance is used to measure the apparent weight W1, when only the sinker is submerged in water.
In (Ill) the spring balance is used to measure the apparent weight W2 when both the cork and the sinker are submerged.
The following observations were made.
W = 0.08N
W = 0.60N
W2 = 0.28N
Use this information to determine the:
(i) Upthrust on cork. 
(ii) relative density of cork. 
(d) Figure 18 shows parts of a simple submarine, a ship that can travel both on water and under water.
To do this water is pumped in or out of the ballast tanks.

​Explain how the tanks are used to change the depth of the submarine.

answers