write a short notes on FORCE AND PRESSURE Class 8th science Formula, diagram and examples must be mentioned please help me..........!
Answers
Answer:
Pressure is defined as the physical force exerted on an object. The force applied is perpendicular to the surface of objects per unit area. The basic formula for pressure is F/A (Force per unit area). Unit of pressure is Pascals (Pa). Types of Pressures are Absolute, Atmospheric, Differential, and Gauge Pressure. While sipping beverages from a straw, have you noticed that you actually suck the air out of the straw? While you sip the beverage, you’re actually applying ‘Pressure’.
Pressure (P) = Thrust/ Area
The SI unit is ‘pascals (Pa)’. 1 Pa = 1N/m2
Example: It is easier to hammer a sharp pin than to hammer a blunt pin. This is because the area at the end of the sharp pin is smaller than the area at the end of a blunt pin. This leads to an increase in pressure leading to hammer the sharp pin easily.
Explanation:
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Answer:
Force:
(i) Force is a push or a pull.
(ii) Living and non- living things can apply force.
(iii) To apply a force over an object interaction between object and source of force is necessary.
(iv) Whenever force act two object are involved. One which applied force, the other which receive force.
Examples: To kick ball we need to push it, to pick the book we need to pull it, to hit the ball we need to push it and to lift the box we need to push it.
Direction and Magnitude of Force:
(i) The measurement of strength and amount of force is called magnitude of force.
(ii) Two or more forces on the same object can be applied in the same direction and opposite direction.
1. When two or more forces are applied over an object in the same direction:
When two or more forces are applied in the same direction, then the total or net force is the addition of magnitude of both the forces.
Example: When two persons push the box in the same direction with the magnitude of forces of each 2 N, then resultant force will be-
Net force:- 2N + 2N= 4N (In the direction of applied force)
When two forces are applied over an object in the opposite direction:
When two forces are applied over an object in the opposite directions, the total effective or net force is the difference of magnitude of two forces.
Example:
(i) When two persons push the box in the opposite direction with the magnitude of forces of each 2 N, then resultant force will be-
Net force:- 2N - 2N= 0N (Box will not move)
(ii) If one person is applying a force of 6 unit in one direction and another person is applying a force of 8 unit in opposite direction,
Then the resultant force: 8N - 6N= 2N (In the direction of higher magnitude force)
In this case, force will act in the direction of higher magnitude of force.
Pressure:
The force acting on per unit area of a surface is called pressure. We can say force per unit area is called pressure.
Pressure = Force / Area
From above formula, we can say that with same applied force, Pressure is indirectly proportional to the area, thus pressure decreases with increase in area and increases with decrease in area.
Example:
(i) When we cut an apple, we need to use the sharp edge of the knife instead of blunt knife because the sharp edge of knife has small surface area and we need to exert less force with high pressure to cut the apple.
(ii) When we put a nail into a wooden board, the pointed end of the nail is kept at the front. The pointed end of the nail has very small surface area and this enables us to apply a greater pressure with the applied force.
Pressure exerted by Liquid and Gas:
(i) Liquid and gas can also exert pressure on inner walls of the container in which they are kept.
(ii) When air is filled, a rubber balloon gets inflated from all sides. This happens due to air or gas exerts pressure over inner walls of the balloon.
(iii) Water starts leaking if there is a pore in the bottle. This happens due to water exerts pressure over the walls of the bottle.