You surely know that the less steep a slope is, the easier is to pull a weight up on it.
How to use?
Set the slope to different angles and pull up the cars. What do you experience?
Setting the slope to different angles, the dynamometer will show various values when you pull the weight upwards. You need less energy to pull up the cars on smaller slopes than on steeper ones but you need to produce energy for a longer way. The product of the power’s amplitude and the road fulfilled is always the same.
These simple machineries –slope, pulley and lever- were already know in antiquity. They were used at building sites for moving great weights. Some people think that slaves pulled up the heavy stones on light slopes when building the pyramids.