Force

Force, Newton's third Law and acceleration

Force is a convenient abstraction to represent mentally the pushing and pulling interaction between objects. 

The unit of force is the Newton (N) - where one newton is one kilogram metre per second squared. Th enewton is defined as the force which, when applied to a mass of one kilogram, gives an acceleration of one metre per second squared.

F = m a   (1)

where 

F = force (N)

m = mass (kg)

a acceleration (m/s2)

It is common to express forces as vectors with magnitude, direction and point of application. The net effect of two or more forces acting on the same point is the vector sum of the forces.

Newton's Third Law

Newton's third law describes the forces acting on objects interacting with each other. Newton's third law can be expressed as

  • "If one object exerts a force F on an other object, then the second object exerts an equal but opposite force F on the first object"

Acceleration

If there is a net unbalance between forces acting on a body the body accelerates. If the forces are balanced the body will not accelerate.

Example - Force needed for Acceleration

A mass of 50 kg is accelerated at 2 m/s2. The force required can be calculated as

F = (50 kg) (2 m/s2

   = 100 N

Example - Force due to Gravity

The force on a mass of 50 kg due to gravity 9.81 m/s2 can be calculated as 

F = (50 kg) (9.81 m/s2

   = 490.5 N

Search the Engineering ToolBox

Engineering ToolBox - SketchUp Edition - Online 3D modeling!

3D Engineering ToolBox - draw and model technical applications

Engineering ToolBox - SketchUp Edition - enabled for use with the amazing, fun and free Google SketchUp

Translate the Engineering ToolBox
About the EngineeringToolbox