What is force? Give it's SI unit ​

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

Awind turbine is rotating counterclockwise at 0.5 rev/s and slows to a stop in 10 s. its blades are 20 m in length. (a) what is the angular acceleration of the turbine? (b) what is the centripetal acceleration of the tip of the blades at t=0s? (c) what is the magnitude and direction of the total linear acceleration of the tip of the blades at t=0s?

Explain why you think this diagram shows what happened to the carbon in the biodome.