Extra Explaining Question - PRESSURE

PRESSURE

1. Explain why divers must breathe out as they rise to the surface?
   
   As the diver ascends from the bottom to the surface, the pressure exerted by water decreases. This decrease in pressure causes the volume of any gas in the diver’s lungs to increase if the diver does not compensate.
2. Why is the atmospheric pressure less at the top of a mountain than it is at the bottom of the mountain?
   
   This is because the atmospheric pressure decreases with the increase of altitude since the weight of atmosphere decreases. At the top of a mountain the weight of the atmosphere is low hence low atmospheric pressure.
3. Use your knowledge of pressure to explain why the pressure increases as you dive towards the bottom of the swimming pool.
   
   The pressure in liquids depends on depth. When you dive towards the bottom of swimming pool the weight of water acting on you increases hence the pressure increases.
4. Why do people suffer from nose bleeding at high altitudes?
   
   Nose bleeding is a result of blood pressure being high than the atmospheric pressure. As a person rises to high altitude, the weight of the atmosphere above him/her decreases and so the atmospheric pressure falls.
   
   As the atmospheric pressure falls, the body’s blood pressure stays the same. This makes the inside pressure (blood pressure) higher than the outside (atmospheric) pressure.
   
   As a consequence, blood pushes harder on the blood vessels and may cause veins to rupture at places where they are weak/thin such as in the nose, thereby resulting to NOSE BLEEDING.
5. Why it is easier to cut a piece of meat using a sharp knife than a blunt knife?
   
   A sharp knife has a smaller cutting edge than a blunt cutting edge. Under the application of the same force, a sharp knife will thus exert more pressure than a blunt one.
6. Why the bottom of the dam is made thicker than the top?
   
   This is because liquid pressure increases with depth, so the pressure at the bottom of the dam is much greater than that at the top; hence the bottom of the dam has to be much stronger than the top.
7. Why the atmospheric pressure at sea level different from that on top of Mount Kilimanjaro?
   
   This is because the atmospheric pressure decreases with the increase of altitude since the weight of atmosphere decreases. At sea level there is high atmospheric pressure while on top of Mount Kilimanjaro atmospheric pressure is low.
8. Why the tyres of a tractor are large and wide?
   
   This is because the larger and wide tyres exert low pressure on the ground.
9. Why a woman wearing shoes with pointed heels is more likely to cause damage to a wooden floor than an elephant?
   
   This is because the shoes with pointed heels have small area of contact with the floor hence resulting high pressure while the elephant exerts low pressure to the floor due to having large area of contact with the floor.
10. Explain why pressure of atmosphere does not break windows?
    
    Because atmospheric pressure is exerted on both sides of a window, so no net force is exerted on the window and hence uniform pressure does not break the window.
11. Use a diagram to describe how manometer can be used to measure the pressure of a gas at a gas-tap.
    
    Manometer is a U-shaped device used to measure gas pressure. When both ends are open, the pressure on both sides are equal.

    

    
    When one end is connected to unknown pressure P₁ the liquid level falls in one arm and rises on the other arm.

    

    P₁ = P₂ + ∆h𝞺g

    The change in height is because of change of pressure.