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Ashley Lew, Maya, Krupa, Tharika, Yi Xuan

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Ashley Lew, Maya, Krupa, Tharika, Yi Xuan

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Q1. To prevent the submarine from getting crushed by the water pressure.
Q2. The outer wall of the submarine should be strong in order to withstand the water pressure and waterproof.

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1. The air pressure inside within the suction cup is lower than that outside the suction cup. Air is pushed out from under the suction cup when it is pressed against the wall, thus the air pressure between the suction cup and the surface decreases. The higher atmospheric pressure holds the suction cup hold in place on the surface.
2. The roughness of the surface of the wall

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1. There is a higher air pressure outside the suction cup than within the suction cup. The higher atmospheric pressure holds the suction cup in place on the surface

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1. When the suction cup presses against the surface, air is pushed out and air pressure between the suction cup and the surface decreases. It becomes lower than atmospheric pressure, the higher atmospheric pressure holds the suction cup in place, allowing it to work
2. Texture of surface,whether the surface is wet or dry
Uses of suction cups:
- massage
- attach things ruining wall
- used in surgeries

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1. When the patients suck on the straw, air is removed from the cup. Thus, the air pressure inside the straw decreases and becomes lower than the surrounding atmospheric pressure. The higher surrounding atmospheric pressure pushes the liquid up the straw and into the patients’ mouths.

2. When the patients suck on the straw, air is removed from the cup. However, since there is a hole in the straw above the liquid level, surrounding air will enter the straw. Thus, the air pressure in the straw will remain the same as the surrounding atmospheric pressure. Due to this, the liquid in the cup will not move up the straw into the patients’ mouths.

Pg 26, 5. When a force is applied on a sharp syringe to draw blood, the area of contact with the syringe is very small. With force and a small area of contact, there will be a high pressure exerted. A high pressure will allow the syringe to pierce the skin and draw blood more easily.

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Q1.
When a patient uses a straw to drink, the air in the straw is sucked out. This causes the air pressure in the straw to decrease and become lower than the atmospheric pressure. Thus, the atmospheric pressure acts downward and presses the liquid up the straw. Hence, the drink travels up the straw and allows the patient to drink water.

Q2.
When there is a hole in the straw that the patient is using, air is able to enter the straw. Thus, the air pressure in the straw does not change and the drink does not travel up the straw. Hence, the patient is not able to drink when there is a hole in the straw.

Table 9.10
When a sharp syringe is used to draw blood, the are of contact is very small. Thus, less force will be needed to exert the same amount of pressure on the syringe as compared to using a wider syringe.

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1a) Area and force
b) heel and toes
c) The back of the high heel has a smaller area of contact with the ground and thus there is a higher amount of pressure exerted on both the heel and toes.

2)The flat heeled shoes has a larger area of contact with the ground compared to the high heeled shoes thus a smaller amount of pressure is exerted on the foot.

The sharp knife has a smaller area of contact with the food than the blunt knife, thus a higher amount of pressure is exerted on the food, allowing the sharp knife to cut the food more easily.

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1a. Surface area and force
1b. Toes
1c. The force at the back of the foot will be transferred to the toes, thus more force and a smaller surface area will exert a greater pressure
2. A flat heeled shoe has more area thus pressure exerted on the ground will be smaller and it will be easier to walk.

9.10
A sharp knife has a smaller surface area with the apple thus exerting a higher pressure on the contact area between the apple and the knife, allowing the apple to be cut more easily compared to a blunt knife that has a larger contact area with the apple

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1)the air pressure within the suction cup is lower than the air pressure out side of the suction cup. the higher atmospheric pressure helps the suction cup to stick to the surface and hold it in place

2) factors that affect the ability of a suction cup to stay fixed on a surface :
-whether the surface is textured or rough
-whether the surface is greasy
-the temperature of the surface

uses of suction cups :
-sticking hooks to the walls for hanging clothes, bags etc
-lifting large heavy things
-sticking cameras to the sides of vehicles when filming a movie

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1. The air pressure between the suction cup and the surface decreases when air is pushed out of the suction cup. The higher atmospheric pressure outside the cup holds it in place thus enabling the suction cup to work.
2. Temperature of surface and texture of surface

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table 9.10
a sharp knife has a smaller contact area with the apple than a blunt knife so less force in needed to exert the same amount of pressure on the apple and cut it

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Table 9.10:

Pressure can crush a submarine if it goes beyond a certain depth underwater. In space, there is no air and thus no air pressure. So the spacesuit worn by an astronaut in outer space protects the astronaut from the lack of air pressure.

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they are used to stick hooks to the wall to hang bags, clothes etc.