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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
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