Couples A couple is a pair of forces that acts to produce rotation only Unlike moments of a single force, the moment of a couple doesn’t depend on a pivot, only on the perpendicular distance betwee...
What is a Moment? A moment is the turning effect of a force Moments occur when forces cause objects to rotate about some pivot The moment of a force is given by Moment (N m) = Force (N) × perpendic...
Centre of Gravity The centre of gravity of an object is the point at which the weight of the object may be considered to act For example, for a person standing upright, their centre of gravity is r...
Elastic Collisions When two objects collide, they may spring apart retaining all of their kinetic energy. This is a perfect elastic collision An elastic collision is one where kinetic energy is con...
The Principle of Conservation of Momentum The principle of conservation of momentum is: The total momentum of a system remains constant provided no external force acts on it For example if two obje...
Terminal Velocity For a body in free fall, the only force acting is its weight and its acceleration g is only due to gravity. The drag force increases as the body accelerates This increase in veloc...
Drag Forces Drag forces are forces acting the opposite direction to an object moving through a fluid (either gas or liquid) Examples of drag forces are friction and air resistance A key component o...
前几天，2022年夏季A-level大考成绩开始放榜。 但在今日，英国《卫报》（the Guardian）爆料——在英国，约有2.8万名A-level学生还没有收到任何大学录取通知书，面临无大学可上的窘境。 约2.8万英国学生目前没有off...
Force & Momentum Force is defined as the rate of change of momentum on a body Force is equal to the rate of change in momentum The change in momentum is defined as the final momentum minus th...
