Answer:
Toward the centre of the circular path
Explanation:
The can is moved in a circular path: this means that it is moving by circular motion (uniform circular motion if its tangential speed is constant).
In order to keep a circular motion, an object must have a force that pushes it towards the centre of the circular trajectory: this force is called centripetal force, and its magnitude is given by

where m is the mass of the object, v its tangential speed, r the radius of the trajectory. This force always points towards the centre of the circular path.
Answer:
Radiation
Explanation:
The sun radiates energy to the earth to make it warmer near the equator.
Bike
because it involves lots of angular mechanics that allow it to balance itself when moving.
all other examples have a constant force being applied into the system which is very easy to formulate, therefore they are simple machines.