Forces

• What does a scalar quantity have?

  Magnitude only
• What does vector quantity have?

  Magnitude and direction
• What is a force?

  A vector quantity
• A force occurs when two or more objects interact.
• Forces are either?

  Contact or non-contact.
• what are contact forces?

  Forces that occur when two objects physically touch each other.
• What are non-contact forces?

  Forces that act on an object without physical contact.
• Give an example of a contact force.


  Friction, air resistance, tension or upthrust
• Give an example of a non-contact force.


  Gravitational force electrostatic force or magnetic force
• What is gravity?

  A force of attraction between all masses
• The mass of an object is related to the amount of matter it contains and is constant.
• What is weight?


  The force exerted on an object due to gravity.
• The weight of an object depends on the gravitational field strength, where the object is, and is directly proportional to its mass.
• The equation for weigh is mass (kg) x gravitational field strength (N/kg)
• What is the equation for weight?

  Weight = mass x gravitational field strength
• What is a resultant force?

  The overall force acting on an object, taking into account both magnitude and direction.
• (HT) What are scale vector diagrams used for?

  To illustrate the overall effect, when more than one force acts on an object
• When drawing a free body diagram, draw the object at rest and show all external forces acting on it.
• in a scale, vector diagram, the forces are added together to find a single resultant force.

  FR = F1 + F2
• Scale vector diagrams can also be used when a force is acting in a diagonal direction. Expressing this force is to forces at right angles to each other, can help to work out what affect the force will have.
• How is a scalar quantity different from a vector quantity?

  A scalar quantity just has size, but a vector has size and direction.
• what is the gravitation of field strength on earth?


  10N/kg
• An astronaut with a mass of 80 kg stands on the moon. What is his weight?

  (g= 1.6N/kg)

  80×1.6= 128 N
• The car troubles in a straight line to the east, with a driving force of 500 N. If total frictional forces are 400 N, what is the resultant force and in which direction does it act?

  Resultant force: 100 N to the east