Forces and Pressure

Force is an interaction that can cause an object to change its speed, shape, or direction of motion
Contact forces are exerted when objects are in physical contact, e.g. pushing, pulling, friction
Non-contact forces act without physical contact, e.g. gravitational, electromagnetic, and magnetic forces
Muscular forces are exerted by the muscles, e.g. lifting a school bag
Electrostatic forces arise from the attraction/repulsion between electrically charged objects
Gravitational forces are exerted by objects with mass, pulling other objects towards them

Contact forces require physical interaction between objects
Non-contact forces act without physical contact, e.g. magnetic and electrostatic forces
Magnetic objects can attract other magnetic objects without touching
Electrically charged objects can attract or repel without physical contact

Pressure is the force applied per unit area on a surface
Greater the force, higher the pressure
Smaller the area, higher the pressure
Examples:
- Pointed objects like pins have high pressure due to small area
- Porters carry heavy loads on their heads by distributing the force over a larger area using a cloth
Pressure in liquids and gases:
- Pressure is exerted equally in all directions
- Holes in a submerged bottle allow water to flow out due to pressure difference### Forces and Pressure
Force: a push or pull that can cause an object to change its motion or shape
Pressure: force applied per unit area
Atmospheric pressure: the pressure exerted by the air in the atmosphere, which is approximately 78.2% nitrogen gas

Force of attraction: a force that pulls two objects towards each other, e.g., gravitational force, electrostatic force
Force of repulsion: a force that pushes two objects away from each other
Frictional force: a force that opposes motion between two surfaces in contact
Gravitational force: a force that attracts two objects with mass towards each other

Contact force: a force that acts through physical contact, e.g., frictional force, normal force
Non-contact force: a force that acts without physical contact, e.g., gravitational force, electrostatic force

Balloon experiment: when a balloon is inflated and then released, it exerts a force on the surrounding air, causing it to expand
Pulling a cart: when you pull a cart, you apply a force to it, which causes it to move
Squeezing a toothpaste tube: when you squeeze a toothpaste tube, you apply a force to the tube, which causes the toothpaste to come out

Newton's first law of motion: an object at rest will remain at rest, and an object in motion will continue to move with a constant velocity, unless acted upon by an external force
Force and acceleration: force is required to change the motion of an object, and the greater the force, the greater the acceleration

Launching a rocket: a rocket requires a massive force to overcome the gravitational force and lift off the ground
Hydraulic systems: hydraulic systems use pressure to transmit forces and perform work, e.g., in car brakes and elevators
Medical applications: forces are used in medical procedures, e.g., in blood pressure measurement and surgical operations

Force is an interaction that can cause an object to change its speed, shape, or direction of motion
Forces can be classified into contact forces (e.g. pushing, pulling, friction) and non-contact forces (e.g. gravitational, electromagnetic, magnetic)

Contact forces require physical interaction between objects
Non-contact forces act without physical contact
Muscular forces are exerted by the muscles (e.g. lifting a school bag)
Electrostatic forces arise from the attraction/repulsion between electrically charged objects
Gravitational forces are exerted by objects with mass, pulling other objects towards them

Pressure is the force applied per unit area on a surface
Greater the force, higher the pressure
Smaller the area, higher the pressure
Examples of high pressure: pointed objects like pins, porters carrying heavy loads on their heads using a cloth
Pressure in liquids and gases: pressure is exerted equally in all directions

Force of attraction: a force that pulls two objects towards each other (e.g. gravitational force, electrostatic force)
Force of repulsion: a force that pushes two objects away from each other
Frictional force: a force that opposes motion between two surfaces in contact
Gravitational force: a force that attracts two objects with mass towards each other

Newton's first law of motion: an object at rest will remain at rest, and an object in motion will continue to move with a constant velocity, unless acted upon by an external force
Force and acceleration: force is required to change the motion of an object, and the greater the force, the greater the acceleration

Launching a rocket: a rocket requires a massive force to overcome the gravitational force and lift off the ground
Hydraulic systems: hydraulic systems use pressure to transmit forces and perform work (e.g. in car brakes and elevators)
Medical applications: forces are used in medical procedures (e.g. in blood pressure measurement and surgical operations)