how to sketch this and what is it called? please help
It is called a cam. I would use a Curve created with a tool in the Curve Maker extension (see the Extension Warehouse for it.) to model it.
For this I used the Bernoulli spiral. One turn. Then connected the ends.
Or, for the following one, an Archimedes spiral of one turn. You can play with first and second radii to get the shape you need.
thanksss dave can u teach me to sketch it im new in sketchup if its okay for you. sorry to bother u
Dave thanks Dave I did it thank you so much
and you could also…
Thank you so muchh