Springs

What is required to change an objects shape and what are examples of this?

Equal and opposite forces, tensile and compressive forces

What do tensile forces produce?

Extension

What do compressive forces produce?

Compression

What does Hooke’s law state?

‘A material’s extension is directly proportional to the force applied to it, within its elastic limit’

Define plastic deformation

When a material cannot return to its original shape once the force applied is removed, making it permanently deformed

Define elastic deformation

When a material can return to its original shape once the force applied is removed, making it temporarily deformed

What is the equation for force applied?

F = ke

F = Force applied, N, kgms^-2

k = Force constant

e = Extension, m

What does the force extension graph of a spring/metal wire look like and its characteristics?

Hooke’s law obeyed, elastic deformation until elastic limit is reached then plastic deformation occurs

What does the force extension graph of a rubber band look like and its characteristics?

Hooke’s law not obeyed, elastic deformation throughout

What does the force extension graph of a plastic/polythene look like and its characteristics?

Hooke’s law not obeyed, elastic deformation until plastic deformation in the form of snapping occurs

What is the equation for total force constant of springs in series?

1 / kt = 1 / k1 + 1 / k2…W

What is the equation for the total force constant of springs in parallel?

kt = k1 + k2…