An iron bar is heated. its length, l, in millimetres can be modelled by a linear function, l= mt + c,
where t is the temperature measured in degrees celsius (°c).
at 150°c the length of the iron bar is 180 mm.

this was already solved by me with a different person. if you look it up in the search bar at the top of the page, you will get the answer.

step-by-step explanation:

i think it will be zero as slope has a formula of difference between initial and final distance divided by itz time interval