forces

• what are examples of scalar quantities?

  mass ,temp, energy ,time ,speed and distance
• what are scalar quantites?

  scalar quantities have magnitude (size) only and do not have a direction
• what are examples of vector quantities?

  displacement,weight,force,velocity,acceleration,momentum
• what are vector quantities?

  they have both magnitude and direction and it is a displacement quantity force is also a vector quantity
• what are contact forces?

  Forces that occur when two objects physically touch each other. tension in the rope is an example.
• what are normal contact forces?

  this force can only happen if the two objects are in direct contact
• what are non contact forces?

  two objects not physically touching each other such as gravitational force
• gravity is a non-contact force because the objects do not need to be touching
• mass of someone on earth is the same everywhere else
• the surface of the earth the gravitational force is 9.8 N/kg
• the gravitational field strength is the measure of the force of gravity in a particular location
• resultant force is a single force that has the same effect as all of the original forces acting together
• to work out the resultant force we subtract the smaller forces from the larger forces
• when several forces act on an object they could be replaced by a single force which has the same effect
• work done (j) = force (N) x Distance (m)
• there are 4 different types of forces:

  air resistance , lift , thrust , weight

  
• the forward force goes right
• the friction force goes left
• a moving object has a kinetic energy store
• the temperature of the brakes increases and at the same time, the car slows down as it uses kinetic energy
• in an elastic material we are applying forces at either ends
• the stretching forces are equal in magnitude but opposite in direction in an elastic material
• elastic materials will always return to their original length or shape if we take away the forces acting on them
• in order to change an objects length or shape then we have to apply more than one force
• Force(n) = k(spring constant N/m) x e(extension ,m)
• normal walking speed= 1.5 m/s running speed= 3m/s cycling speed= 6m/s
• if an object moves at a constant speed in a circle then its velocity is constantly changing even though its speed is constant
• weight is measured using a newtonmeter
• Work done against the frictional forces acting on an object causes a rise in the temperature of the object.
• The extension of an elastic object, such as a spring, is directly proportional to the force applied, provided that the limit of proportionality is not exceeded
• When a force causes an object to move through a distance work is done on the object.
• A vector quantity may be represented by an arrow. The length of the arrow represents the magnitude, and the direction of the arrow the direction of the vector quantity.