TOPIC 5 : FORCES

• a scalar are quantities that only have an magnitude
• a vector have both magnitude and direction
• a vector is represented through an arrow
• a force is a push or pull that acts on an object due to the interaction with another object
• magnitude is measured in newtons
• weight is the force of gravity on a mass
• mass Is the amount of matter in an object (measured in kg)
• W (weight) = m (mass,kg) x g (gravitational field strength,N/Kg)
• resultant force is a single force that describes all forces operating on a body
• combined action is when one or more forces are acting on an object they can be added together to produce one final force
• tension is a force experienced by a rope, string, or cable when it is pulled from the opposite ends
• upthrust is the upward buoyancy force acting on an object when it is on a fluid
• work is done when an object is moved over a distance by a force applied in the direction of its displacement
• W (work done J or Nm) = F (force, N) x S (distance, m)
• work done = energy transferred
• friction is a force that works in opposition to the motion of an object
• at least 2 forces must be applied to change shape
• stretching, bending, compressing cause to change shape
• compression occurs when a physical force presses inward causing it to become compacted
• stretching is caused by a pulling force
• bending is when a force acts on a linear material causing it to deform, typically in a curved manner
• elastic deformation is when an object returns to their original shape when the stretching force is removed
• inelastic deformation is when objects remain stretched and do not return completely to their original shape even when the stretching force is removed
• plastic material is a material that does not go back to its original shape
• hooke's law : the extension of a string which is directly proportional to the force applied, as long as, the limit of proportionality is not exceeded
• spring constant represents how stiff a spring is - higher the spring constant the stiffer it will be
• a moment is a turning effect of a force, the turning happens around a pivot
• to be in an equailibrium, the total clockwise movement has to equal to the total anti - clockwise movement
• a system error is when there are faults in the apparatus for experimental methods which consistently affect every measurement
• parallex error is an error that occurs due to incorrect positioning of the eyes while taking a reading on a measuring scale