1.1 (f)
Contents
Demonstration 1
This demo links F=ma with a=(v-u)/t. Start with a trolley on an air track, two light gates and the trolley attached to a mass. Increase the angle of the air track until the wight of the mass balances the component of the weight of the trolley. Cut the string, measure v, u & t to find a. Check this value using F=ma knowing F and m.
Resources
Analysis
use a=(v-u)/t to find the acceleration. Compare this value to a=F/m. It is very helpful to draw a LARGE diagram and identfy the newton pairs and the forces acting on the trolley.
Equipment
Air track, trolley, pulley, masses, string, lab. jack, PASCO light gate kit.
Safety
Make sure the mass does not land on someone's foot.
Demonstration 2
This can be used to check what they have learnt! Same setup, but trolley at the far and of the track from the pulley, so use a long piece of string! Get the pupils to work out what the acceleration will be of the trolley with the track horizontal. It is useful to have the mass as a significant fraction of the mass of the trolley.
Resources
Analysis
They do a caculation first to work out what the acceleration will be. They take measurements of v, u & t to find a.
Equipment
Air track, trolley, pulley, masses, string, lab. jack, PASCO light gate kit.
Safety
Make sure the mass does not land on someone's foot.
