General Physics 1 PDF

Force – a push or a pull by another object; vector quantity Contact Force – force between two bodies that are in direct contact with each other Ex: Applied force, friction, tension, normal force Noncontact Force/ Action-at-a-Distance Force – force that acts even if the interacting bodi...

Force – a push or a pull by another object; vector quantity Contact Force – force between two bodies that are in direct contact with each other Ex: Applied force, friction, tension, normal force Noncontact Force/ Action-at-a-Distance Force – force that acts even if the interacting bodies are separated by a distance Ex: Four Fundamental Forces of Nature  Four Fundamental Forces of Nature 1. Gravitational Force – attractive force exerted by objects with mass 2. Electromagnetic Force – force that holds atoms and molecules together 3. Strong Nuclear Force – force between protons and neutrons in a nucleus 4. Weak Nuclear Force – plays role in the radioactive decay of some nuclei Newton’s 1st Law: Law of Inertia “A body at rest will remain at rest and a body in motion will continue to move at constant velocity unless acted upon by an unbalanced external force.” ෍𝑭 = 𝟎 Net Force/ Resultant Force – vector sum of all the forces acting on a body Unbalanced Force – a resultant force that is not equal to zero Inertia – property of a body that tends to resist change in its state of motion Mass – measure of inertia Inertial Reference Frame – reference frame that is at rest, moving at constant velocity with respect to an observer, or moving at constant velocity with respect to an inertial frame. *Why do we need to wear seatbelts when we are riding a car?” Newton’s 2nd Law: Law of Acceleration “The acceleration of an object is directly proportional to the net external force acting on the object and inversely proportional to the mass of the object.” ෍ 𝑭 = 𝒎𝒂 SI Unit: newton (N) Components in 3D space: σ 𝐹𝑥 = 𝑚𝑎𝑥 σ 𝐹𝑦 = 𝑚𝑎𝑦 σ 𝐹𝑧 = 𝑚𝑎𝑧 * Which is harder to push: an ant or elephant? Why? Property Static Kinetic The force of friction that acts The force of friction that acts between two surfaces with the between two surfaces that are in Definition tendency to move is called static motion against each other is friction. called kinetic friction. Denoted as μs μk Expression fs=μsN fk=μkN Value 0 to 1 or greater than 1 0 to 1 or greater than 1 When it acts at rest when moving along a surface A man pushing a heavy block that Example does not move. A ball rolling on a table. Newton’s 3rd Law: Law of Interaction “For every action, there is an equal but opposite reaction.” Action-Reaction Pair – pair of forces exerted by two bodies to one another; equal in magnitude but opposite in directions *Why can we walk? *Why do firemen hold the fire hose tightly? 𝑭𝑨 𝒐𝒏 𝑩 = −𝑭𝑩 𝒐𝒏 𝑨 Free Body Diagram: Normal Force Free Body Diagram: Friction Force Free Body Diagram: Tension Force Free Body Diagram: Weight