Classify the following amongst the contact and non-contact forces:
i) frictional force,
ii) normal reaction force
iii) force of tension in a string,
iv) gravitational force
Contact force: frictional force, normal reaction force, force of tension in a string
Non-contact force: gravitational force
Contact force: frictional force, normal reaction force, force of tension in a string
Non-contact force: gravitational force