WAEC Physics 2013 Objective — Question 20
Question 20 of 50 from the West African Examinations Council (WAEC) Physics 2013 Objective paper, with the correct answer and a full explanation.
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The outlet of a bicycle pump is used to inflate a football as illustrated in the diagram above. Why does the pressure of the air inside the pump increase as the pump handle is slowly pushed downward at constant temperature?
- A. Momentum of the air molecules is increased
- B. Volume occupied by the molecules is increased
- C. Frequency of collision of the air molecules with the walls of the pump is increasedCorrect
- D. More air molecules are colliding with one another in the system
Explanation
When the pump handle is pushed down, the volume of the air in the pump decreases, causing more collisions between the air molecules and the pump's interior walls, increasing pressure. (The collisions responsible are between the air molecules and the walls, not between the air molecules themselves.)
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