Forces in Physics

Force

• A push or pull that causes an object to change its motion or shape
• Can be either contact (direct) or non-contact (indirect)
• Measured in Newtons (N)

Types of Forces

• Gravity: the downward force that attracts objects towards each other
• Friction: the force that opposes motion between two surfaces in contact
• Normal Force: the force exerted by a surface on an object that is in contact with it
• Tension: the force exerted by a stretched string or wire
• Air Resistance: the force that opposes the motion of an object through the air

Newton's Laws of Motion

First Law (Law of Inertia)

• 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
• Inertia: the tendency of an object to resist changes in its motion

Second Law (Law of Acceleration)

• Force (F) is equal to the mass (m) of an object multiplied by its acceleration (a): F = ma
• The more massive an object, the less it will accelerate when a force is applied
• The greater the force applied, the greater the acceleration of an object

Third Law (Law of Action and Reaction)

• For every action, there is an equal and opposite reaction
• When two objects interact, they apply forces to one another that are equal in magnitude and opposite in direction

Motion

Types of Motion

• Translational Motion: motion in a straight line
• Rotational Motion: motion around a fixed axis
• Circular Motion: motion in a circular path

Describing Motion

• Displacement: the distance an object travels from its initial to its final position
• Velocity: the rate of change of an object's displacement with respect to time
• Acceleration: the rate of change of an object's velocity
• Speed: the rate of change of an object's distance traveled

Force

• A push or pull that causes an object to change its motion or shape
• Can be either contact (direct) or non-contact (indirect)
• Measured in Newtons (N)

Types of Forces

• Gravity: attracts objects towards each other
• Friction: opposes motion between two surfaces in contact
• Normal Force: exerted by a surface on an object in contact
• Tension: exerted by a stretched string or wire
• Air Resistance: opposes motion of an object through the air

Newton's Laws of Motion

First Law (Law of Inertia)

• An object at rest remains at rest, and an object in motion continues with constant velocity unless acted upon by an external force
• Inertia: resistance to changes in motion

Second Law (Law of Acceleration)

• Force (F) = mass (m) × acceleration (a): F = ma
• More massive objects resist acceleration
• Greater force applied means greater acceleration

Third Law (Law of Action and Reaction)

• Every action has an equal and opposite reaction
• Interacting objects apply equal forces in opposite directions

Motion

Types of Motion

• Translational Motion: motion in a straight line
• Rotational Motion: motion around a fixed axis
• Circular Motion: motion in a circular path

Describing Motion

• Displacement: distance from initial to final position
• Velocity: rate of change of displacement with respect to time
• Acceleration: rate of change of velocity
• Speed: rate of change of distance traveled

A quiz on forces in physics, including gravity, friction, normal force, and tension. Learn about the types of forces and how they are measured.