Dynamics Newton’s Laws

A force is a physical quantity that can affect the motion of an object. Since a force has magnitude, direction, and a point of application, it is a vector quantity. Sir Isaac Newton was the first person to clearly describe the relationship between force, mass & motion. Newton's laws of motion not only apply on Earth but are true throughout the universe.

Different Common Types of Forces 1.Buoyant Force - produced by fluids; acts upward 2.Elastic Force - produced by stretching, compressing, or twisting an object 3.Electrical Force - produced by interaction between charged particles 4.Frictional Force - produced when one surface moves over another; acts in a direction resisting motion. 5.Gravitation Force produced by attraction of any two objects, acts downward on Earth 6.Magnetic Force - produced by interaction of at least 1 magnet and another object.

Newton's 1 st Law of Motion: If there is no force acting on a body, it will continue in its state of rest or will continue moving along a straight line with uniform speed This law is known as the law of inertia.

Newton's 2nd Law of Motion: The effect of an applied force is to cause the body to accelerate in the direction of the force. The acceleration is in direct proportion to the force and in inverse proportion to the mass of the body. In other words, the more force, the more acceleration and the more mass, the less acceleration. If a force is applied to a body at rest, the body will begin to move. If the body is is moving in a straight line and a force is applied in the direction of motion, the body will accelerate. If the force is applied in a direction not in line with the motion, the acceleration will be in the direction of the force.

Reworking our proportion statement, we find we get the equation: Units F- Newtons (N) m= kilograms (kg) a = metres/sec./sec. (m/s 2 ) Combining the units for mass and acceleration, we come up with the unit for force kg m/s 2. This has been defined as one newton (1 N).

Newton's 3 rd Law of Motion: When one body exerts a force on another, the second body exerts on the first a force of equal magnitude in the opposite direction. This occurs at all time in nature. There is always an action force and a reaction force. For example, a book lying on table exerts a force on the table and the table exerts a force on the book.