Forces & the Laws of Motion. Chapter 4. 4.1 Changes in Motion. Objectives : Explain how force affects the motion of an object Distinguish between contact forces and field forces Interpret and construct free-body diagrams. Force. What is a force?
A grain truck filled with soy beans accelerates along the highway at 0.50 m/s2. If the driving force on the truck remains the same, what happens to the acceleration of the truck if soybeans leak from it at a constant rate?
Answer: The loss of soy beans is a decrease in mass. Since a = ΣFnet /m , acceleration increases.
Force of gravity acting on a mass
Fg = mg W = mg Fw = mg
contact force exerted by one object on another in a direction ┴ surface of contact
contact force that opposes motion….
opposes applied force
force exerted by environment on motionless body to resist applied force
force exerted by environment on moving object to resist applied force
Types and smoothness
μs = Fs / FN μk = Fk/ FN