Notes+CH15

**Energy-**

 * The ability to do work.

Work = Force x Distance (have to be in the same direction) (newton-meter) = newton x meters 1Nxm = 1 Joule (J)
 * Work is a transfer of energy


 * Kinetic Energy**
 * energy of any moving object
 * depends on mass and speed (velocity)

 Kinetic Energy = ½ mass x velocity²
 *  KE = ½ mv²


 * double the mass -> double the KE
 * double the velocity ---> quadruple the KE


 * Potential Energy (P.E.)**
 * Energy that is stored as a result of position or shape

Gravitational P.E.  Power - the rate of doing work   > >>
 * P.E. = mass x gravity x height
 * PE = m x g x h
 * Faster rate means more power
 * To Increase power, we can do 1 of 2 things:
 * increase the amount of work done
 * can do a given amount of work in less time
 *  Power = Work /Time
 * P = W / t
 * Units for power = joules/second, watts, horsepower
 * <span style="color: rgb(36, 163, 31);">1 Joule/second = 1 watt
 * <span style="color: rgb(36, 163, 31);">1 horsepower (hp) = 746 watts

Fluid Pressure-the result of a force distributed over an area. ex. bicycle seat vs. recliner; pencil point vs. eraser

In the formula, <span style="color: rgb(206, 13, 13);">force should be in newtons (N) and area should be in square meters (m2). The resulting unit, newtons per square meter <span style="color: rgb(25, 174, 31);">(N/m2), is the SI unit of pressure, also known as a ** pascal ** (Pa). The pascal is named for French scientist Blaise Pascal (1623–1662). Pressures are often stated in units of kilopascals (kPa). Note that 1 kPa is 1000 Pa.

<span style="color: rgb(0, 84, 255);">EXAMPLES done in CLASS A 245 Kg mass measures 8.0 cm in width and 15.0 cm in length. What pressure is it exerting on the floor? Write formula: P = F/A ; P = 2400 N / 120 cm²; P = A = l x w ; A = 8.0 cm x 15.0 cm ; A = 120 cm² F = m x g; F = 245 x 9.8 m/s²; F = 2401 rounded to 2400 N P = F/A ; P = 2400 N / 120 cm² ; P = 20. N/cm²

Consider a box with a weight of 2700 N resting on the ground. If the area is 1.5 m², what is the pressure? Write formula: P = F/A; P = 2700 N / 1.5 m² ; Pressure = 1800 N/m² or 1800 Pa

<span style="color: rgb(0, 53, 255);">REVIEW in class What is energy? The ability to do work What is mechanical energy? True or False: Displacements in opposite directions add together How is speed calculated? What are the standard units of distance and time? Which is longer, 0.25 cm or 25 m? What happens to the spacing of the particles within a solid or liquid as the temperature increases? What happens to eh speed of the particles in a solid, liquid or gas as the temperature is increased?