Forces

*Chapter 10

*Forces

*Force

*A force is any push or pull on an object

*Forces are measured in Newtons (N)

*Forces are vectored quantities that shows both magnitude and direction.

*Forces

*When forces are parallel, they can be combined by either addition or subtraction, to obtain the net force

*Forces

*When forces are perpendicular (right angle) to each other, we use the Pythagorean Theorem

(a2 + b2 = c2)

to find “c” the hypotenuse of a right triangle, to find the net force

*Forces

*A few rules regarding perpendicular forces:

*Always re-draw your force vectors so that the head of one vector is touching the tail of the other one

*Draw your net force vector from the tail of the 1st vector to the head of the 2nd vector

*Forces

*When forces are not parallel or perpendicular, they can be combined by using trigonometric functions of angles (math skills we haven’t learned yet) to find the net force.

*Forces

*Types of Forces

*Mechanical – when you use any part of your body or an extension of your body (bat, racket, stick, hammer, etc.) to apply a force

*Forces

*Types of Forces

*Electrical – the movement of electrons to cause something to happen (motor turning, lights shining, wires to heat up, etc.)

*Forces

*Types of Forces

*Chemical – the force that holds compounds together or are released in a chemical reaction

*Forces

*Types of Forces

*Nuclear – the forces that holds atoms together or that are released in a nuclear explosion

*Forces

*Types of Forces

*Gravitational – a force of attraction between any 2 objects

*Forces

*Types of Forces

*Friction – a force that opposes motion

*forces

*Types of Forces

*Elastic – the rebound force found in rubber bands, springs and bouncing balls.

*Forces

*In the late 1600s Sir Isaac Newton developed the 3 Laws of Motion.

*Forces

*Newton’s 1st Law of Motion states that a body at rest will stay at rest and a body in motion will stay in motion unless acted upon by an unbalanced outside force.

*Forces

*According to Newton’s 2nd Law of Motion, the formula for force is mass times acceleration

*F = m(Kg)* a(m/s/s)*From the formula, the units for force is

*Kg*m/s/s*This is called a Newton (N)

*Forces

*Newton’s 3rd Law of Motion is known as the “action-reaction” law because it states that for every action there is an equal and opposite reaction.

*This explains why when riding on a skateboard when you push backwards on the ground you are propelled forward or

*Why in a rocket the gases push downward to cause the rocket to go up.

*Forces

*Forces

*Forces