Dynamics

Understanding forces, Newton's laws, and how forces cause motion

Topics

How does centripetal force work?

Centripetal force is the force that keeps an object moving in a circular path, always pointing toward the center of the circle. It doesn't create the motion but changes the direction of velocity, causing the object to curve instead of moving in a straight line.

How does conservation of momentum work?

Conservation of momentum states that the total momentum of a closed system remains constant unless acted upon by external forces. When objects collide or interact, their individual momenta may change, but the total momentum before and after the interaction remains the same.

How does Newton's first law work?

Newton's first law states that an object at rest stays at rest, and an object in motion continues moving at constant velocity unless acted upon by an unbalanced force. This describes the property of inertia.

How does Newton's second law work?

Newton's second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This is expressed as F = ma (force equals mass times acceleration).

How does Newton's third law work?

Newton's third law states that for every action, there is an equal and opposite reaction. When object A exerts a force on object B, object B simultaneously exerts an equal and opposite force on object A.

What is angular momentum?

Angular momentum is a measure of how much rotational motion an object has, calculated as the product of its moment of inertia (rotational mass) and angular velocity (rotational speed). Like linear momentum, angular momentum is conserved unless acted upon by an external torque.

What is momentum?

Momentum is the quantity of motion an object has, calculated by multiplying its mass by its velocity. It describes how difficult it is to stop a moving object and is conserved in collisions.

What is torque?

Torque is a measure of how much a force causes an object to rotate around an axis. It's calculated as force multiplied by the distance from the axis of rotation (lever arm), and it determines how effectively a force can cause rotational acceleration.

Why do spinning objects stay upright?

Spinning objects stay upright due to conservation of angular momentum and gyroscopic stability. The spinning motion creates angular momentum that resists changes in orientation, making the object stable and able to maintain its upright position even when disturbed.

Why do we have friction?

Friction exists because surfaces are not perfectly smooth—microscopic bumps and irregularities on surfaces interlock and resist motion. Friction helps us walk, grip objects, and control motion.