P2: Physics - Forces

• An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
• What is a scalar?

  A scalar quantity has magnitude (size) only.
• What is a vector?

  A vector quantity has magnitude and direction
• Is a force a vector?

  Yes
• What is a contact force?

  When the objects are actually touching

  Eg. Friction, Air Resistance, Tension
• What is a non-contact force?

  The objects are not touching

  Eg. Gravitational Force, Electrostatic Force, Magnetic Force
• What is gravity?

  Gravity is a force of attraction between all masses.
• Difference between mass and weight?

  Mass: the amount of matter an object contains and wether it is consistent

  Weight: force acting on an object due to gravity
• Resultant Forces

  When more than one force acts on an object, they can be seen as a single force that has the same effect as all the forces reacting together
• What is work done?

  When a force causes an object to move

  1 joule of work is done when a force of 1 newton
• To change shape of an object

  more than one force must be applied
• If an object returns to its original shape it has been

  Elastically Deformed
• If an object does not return to its original shape it has been..

  inelastically deformed
• What is the extension of an object proportional to?

  the applied force
• What will happen once the limit of proportionality has been exceeded?

  -Doubling the force will no longer double the extension

  -the relationship becomes non-linear

  -the force-extension graph will stop being a straight line
• What does the previous card also apply to?

  The compression of an elastic object.
• The spring constant indicates what?

  How easy it is to stretch or compress a spring eg. higher the constant stiffer the spring.
• A force that stretches or compresses the spring stores what in the spring?

  Elastic Potential Energy
• What amounts are equal provided the spring does not go past the limit of proportionality?

  Work done and energy stored
• When a force causes an object to rotate, the turning effect is called the..

  moment of a force
• If an object is balanced then..

  the total clockwise movement is equal to the anticlockwise movement about that pivot
• Levers and gears can be used to...

  -transmit the rotational effect of forces

  -magnify either the size of the applied force or the distance the force moved over
• When the applied force moves further than the transmitted force the force is...

  increased
• When the applied force is bigger than the transmitted force the distance is...

  increased
• What causes pressure?

  The collision of particles on the surface of its container, the collisions create a force called normal.
• What is the atmosphere?

  A thin layer of air around the Earth
• The greater the altitude the...

  less dense the atmosphere and the lower the atmospheric pressure
• At high altitude there is...

  less air above a surface than at lower altitudes, so there is smaller weight of air acting on the surface
• Pressure at a particular point in a column on liquid depends on?

  -The height of the column above the point

  -The density of the liquid
• The higher the column and the more dense the liquid depends on:

  -The greater the weight above the point

  -The greater the force on the surface at that point

  -The greater the pressure
• Upthrust is..

  The upwards force exerted by a fluid on a submerged object.
• Distance is a scalar quantity 


  -It is how far an object moves

  -It does not take in account direction the object is travelling
• Displacement is a vector quantity 


  -It has magnitude, which is how far the object has travelled from the start

  -measured in a straight line

  -It has direction
• Speed is a....

  scalar quantity
• Velocity is a....

  Vector quantity
• Velocity is..

  The speed of an object in a direction
• When travelling in a straight line the speed and velocity are..

  Constant
• An object travelling in a circle can have...

  constant speed but the velocity is still changing
• Newtons first law is..

  An object will remain in the same state of motion unless acted on by an external force
• The tendency for object to continue in the same state of motion is called..

  Inertia