8th class force and pressure
Answers
Answer:
force = mass ×acceleration
pressure =force / area
Answer:
Vector
– Vector quantities are expressed in magnitude as well as the direction of the object. E.g: Velocity, displacement, weight, momentum, force, acceleration etc.
– Vectors are used to find the resultant component acting on a body.
– When multiple forces act on a body, they can be resolved into one component known as the net force acting on the object.
– A force is an effort that changes the state of an object at rest or in motion.
– It can change an object’s direction and velocity.
– Force can also change the shape of an object.
Explanation:
Contact
A touch or contact is required to do most of our everyday activities. E.g Lifting, pulling, kicking, pushing etc.
Forces that require a touch or contact to be applied are known as contact forces. E.g: Muscular forces, frictional forces
Muscular force
The force applied by the effort of our muscles e.g lifting a heavy box, pulling a bucket of water, pedalling a cycle.
Non-contact forces
Forces that do not need a contact, or that have their influence without a touch.
Example: magnetic force, electrostatic force, gravitational force.
Gravitational force
The attractive force that a body experience towards the centre of the earth is called the force of gravity due to earth.
Property of the universe, every object attracts or exerts a force on every other object.
Electrostatic force
The force of attraction or repulsion experienced by a charged body from another charged body in the same vicinity is known as Electrostatic Force.
Nuclear forces
The nuclear force acts between all the particles in the nucleus. i.e., between two neutrons, between two protons and between a neutron and a proton.
It is an attractive force in all cases.
It is the force that keeps the nucleus intact by overcoming the enormous repulsive force between positive protons.
Thrust and Pressure
Pressure
Force acting per unit area is known as pressure.
P=forcearea
SI unit is Pascal.
Distribution of pressure
Force acting on a smaller area applies more pressure than the same force acting on a larger area.
Examples: Porters place a round cloth on their heads to increase surface area and reduce pressure.
A sharp knife cuts better as more pressure is exerted over a smaller area.
Pressure in fluids
The pressure exerted by a fluid(gases or liquids) in a container is transmitted undiminished in all direction on the walls of the container.
Upthrust
The upward force exerted by a fluid on an object is known as upthrust or buoyant force.
Atmospheric Pressure
Gaseous pressure
Gases exert the same pressure on the walls of the container in all directions.