What is the force that opposes motion between two surfaces in contact?

---

=> What is the SI unit of force?
=> Which of the following is a vector quantity?
=> What is the formula for density?
=> What is the unit of electric current?
=> The SI unit of magnetic flux is:
=> The phenomenon of splitting of light into its component colors is known as:
=> Which of the following is a greenhouse gas?
=> In a parallel circuit, the voltage across each component is:
=> What is the speed of light in a vacuum?
=> The process of converting a gas into a liquid is called:
=> Who formulated the laws of motion?
=> Which particle is positively charged?
=> What is the force that opposes motion between two surfaces in contact?
=> Who discovered the electron?
=> What is the boiling point of water in Celsius?
=> What is the unit of frequency?
=> In which state of matter do particles have the most energy and move freely?
=> What is the formula for acceleration?
=> Who discovered X-rays?
=> What is the force that opposes the motion of an object through a fluid?