SPM QUESTION YEAR 2010

9. (a) The weight of a body is the gravitational force acting on the body.

   (b) (i) - The weight of the father is higher than the weight of the boy.

            - The volume of water displaced by the father is bigger than the volume of water displaced by the boy.

             - The buoyant force that acts on the father is greater than that on the boy.

        (ii) - When the volume of water displaced increases,the buoyant force                                                                 - When the weight of the water displaced increases,the buoyant force increases.

       (iii) Archimedes' principle  

   (c) - When the wooden block is submergedin water,buoyant force is greater than its weight.

        - Hence the buoyant force pushes the block upwards.

        - This occurs until the block reaches the surface when the weight of water displaced, i.e. the buoyant  

           force decreases and becomes equal to the weight of the block causing it to float.

   (d) (i) Streamline line shape to reduce water friction.

        (ii) Use light material like bamboo to make raft float.

       (iii) Larger size raft easier to accommodate participants.

       (iv) Tie the bamboo in the layers.Put the motor the end of the raft to increase the speed of the raft.

        

Exercise :)

(a) Find the maximum buoyant force 
     experienced by the boat.


    -The maximum buoyant force experienced by the 
       boat is 17400 N.


(b) If two men of mass 60 kg and 70 kg 
     intend to travel in this boat,who is 
     more eligible to go in the boat?
     Explain your answer.


    -The men with 60 kg is more eligible because the 
       the men with 60 kg is more mild and light than
       men with 70 kg.Also the boat will not easily to
       sink or wreck when the men with 60 kg is go to
       the boat.





6.The diagram shows a hydrometer.




(a) What is the use of a hydrometer ?



     -The use of hydrometer is to measure the relative
        density of liquids.


(b) What is the purpose of having lead 
      shot at the bottom of the hydrometer?


       -The purpose is to keeps the hydrometer upright.


(c) Explain why the hydrometer is 
     calibrated in such a way that the 
     readings of the scale is increasing 
     downwards. 


     -The volume of liquid displaced decreases when 
        density of liquid increases.The height of hollow
        tube from surface increases.

There are many types applications of Archimedes' Principle.....

 

After discuss, my group choose to take hot air balloon for application of this principle.This is because we can understand this application easily.

 

Hot-air balloon

The atmosphere is filled with air that exerts buoyant force on any object.

A hot air balloon rises and floats due to the buoyant force (when the surrounding air is greater than its weight). It descends when the balloon weight is more than the buoyant force. It becomes stationary when the weight = buoyant force.

The weight of the Hot-air balloon can be controlled by varying the quantity of hot air in the balloon.

 

INFO ZONE:

Balloons are filled with helium gas which is lighter than air After heating, it becomes even lighter. Hot air that rises and cool air sinks to the bottom.

Yang benar,     

            syafiq