forces+elasticity

• how can we stretch, bend or compress objects?

  by applying forces to them. for this to happen, there must be 2 or more forces acting on the object. If there is only one, the object will just move in the direction of that force.
• what is an inelastically deformed object?

  an object that will not return to its original shape when the force stops.
• what is an example of a inelastically deformed object?

  a car, after a car has crashed into a tree, it will not return to its orginal shape.
• what is an elastically deformed object?

  an object that will return to its original shape when the force stops.
• what is an example of an elasticallu deformed object?

  a spring, a spring returns to its original shape when forces stop acting on it.
• what is on the x and y axis of an extension-load graph?

  x axis: extension of the spring

  y axis: the force acting on a spring
• on an extension-load graph, what is it like when there is a low force?

  the graph is a straight line which passes through the origin.
• when no force acts on the spring, there is no extension.
• what happens to the graph as the force increases?

  the spring reaches its limit of proportionality. The straight line on the graph will begin to curve.
• how does the spring constant affect the stiffness of the spring?

  the higher the spring constant, the "stiffer" the spring and the more force is needed to stretch it.
• when a spring is stretched, what is the increase in the length called?

  its extension
• what is the equation for Hooke's law?

  force = spring constant x extension
• how do you investigate Hooke's law?

  1. measure the original length of the spring
  2. hang different masses on the spring and measure the length of the spring in each case
  3. adding masses to the spring increases the downwards force as each mass has a weight
  4. the extension of the spring = length of spring with masses - original length of the spring
• the spring constant is the stiffness of the spring
• what is the limit of proportionality?

  the point where hooke's law breaks down
• what happens if a spring is stretched too much?

  it will not return to its original length when the force stops acting on the spring.
• when we compress a spring, what is stored in the spring?

  elastic potential energy is stored in the spring.
• what is the elastic potential energy stored in a spring equal to?

  the work done when stretching it
• what does the area under the force-extension graph equal?

  the elastic potential energy stored in a stretched spring.
• what is the equation for elastic potential energy?

  elastic potential energy = 0.5(spring constant) x (extension)^2