Chap 7 Pressure Flashcards
Define pressure.
pressure is defined as the force acting per unit area. The SI unit of pressure is newton per square metre (Nm^-2) or pascal (Pa).
What is the formula for pressure?
Pressure = Force/Area
Why is there pressure in liquids?
Liquids have weight due to the Earth’s gravitational pull. Thus, a body of liquid exerts pressure on an object placed in it because of its weight. The amount of pressure inside a body of liquid increases with its depth.
Why are liquids used to transmit pressure?
Liquids are incompressible and hence can be used to transmit pressure. And the principle of pressure allows us to multiply a force. Examples of this is a hydraulic garage lift.
What is atmospheric pressure?
Earth is surrounded by a layer of air called the atmosphere which weighs down on us and the Earth surface. This exerts a pressure on us and the Earth’s surface and is called atmospheric pressure. The atmospheric pressure at sea level is 1.013 x 10^5.
What instruments do we use to calculate atmospheric pressure and gas pressure respectively?
Barometer and Manometer.
Why is there a vacuum at the top of the glass tube of a barometer?
A vacuum ensures that no pressure is exerted over the liquid column in the glass tube.
What determines the atmospheric pressure when using a barometer?
The vertical height of the liquid in the glass tube is the sole variable to atmospheric pressure. Even if the column is tilted or the cross-sectional area of the tube is varied, the height of the column remains the same.
