e.g gravitational force

• Applied force


  A force that is applied to an object
• Attractive force


  One object attracts another
• biofuel - energy source derived from organic matter.
• force - a push or a pull
• motion - the change in position of an object.
• net force - total amount of force acting on an object,
• normal force - force that opposes gravity and is perpendicular
• orbit - a path described by one body about another\
• viscosity - measure of its resistance to deformation.
• balanced force - act on the same object , in opposite direction , and are equal in size.
• unbalanced force - acting on the object.
• gravity - the force of gravity pulls the earth towards the sun and keeps the planets in orbit.
• standard gravity - the specific acceleration that all objects fall at.
• free falling - no other forces are acting on the objects except for gravity
• law of universal gravitation - all objects in the universe attract each other with a force that depends on their masses