Chapter+5+Energy

Chapter 5 Energy - Ben Shank

__Energy__ – the amount of work that can be performed by a force Energy = Work

Work = (Force) x (Distance)

There are several forms of energy: -Kinetic -Gravitational -Potential -Elastic

__Kinetic Energy__ – The energy of an object due to its motion. Equal to the work needed to accelerate a body from rest to its current velocity. KE = ½(m)(v) Kinetic Energy = ½ multiplied by mass and velocity

__Work-Kinetic Energy Theorem__ – The net work done on an object is equal to the change in the kinetic energy of the object. net Work = KE

__Gravitational Potential Energy__ – The energy an object possesses because of its position in the gravitational field. Gravitational Potential Energy = mgh Gravitational Potential Energy = (mass)(free-fall acceleration of gravity)(height)

__Elastic Potential Energy__ – The potential energy in a stretched or compressed object. Elastic potential Energy = ½(k)(x)^2 Elastic Potential Energy = ½(spring constant of object)(distance stretched or compressed)^2

__Conservation of Energy__ – The total energy within a closed system remains constant. KE initial + PE initial = KE final + PE final Kinetic energy decreases as potential energy increases and potential energy decreases as kinetic energy increases within a closed system.

__Total Mechanical Energy__=KE+PE

__Power__-The rate of energy transfer over a period of time.

Measured in Watts: 1 W = 1 J/s = 1 (kg)(m^2)/(s^2) Also, 1 Horsepower = 550 (ft)(lb)/(s) = 746 W

=(video clip) Important concepts for Work and Energy:=

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=Equations frome this chapter:= =**__Sample Problems:__**=



=**__Multiple Choice Problems:__**= =1a) A force of 10 N is applied to an object and the object moves 10 m in the direction of the force. What is the total work done on the object?=

a) 1 J b) 10 J c) 100 J d) 1000 J e) None of the above

=1b) What is the mass of the object?=

a) 1 kg b) 10 kg c) 100 kg d) Unable to be Determined e) None of the above

=2) A waiter uses an upward force of 10N to carry a tray 10 m. What is the total amount of work the waiter does on the tray?=

a) 1 J b) 10 J c) 100 J d) 1000 J e) None of the above

=3) If the velocity of an object doubles, its kinetic energy __.=

a) Is half as much (x1/2) b) Stays the same (x1) c) Doubles (x2) d) Quadruples (x4) e) None of the above

=4) A 10kg ball with an initial velocity of 10m/s rolls down a 10m hill. If the acceleration of gravity is 10 m/(s^2), what is the ball's final kinetic energy?=

a) 0 J b) 500 J c) 1000 J d) 1500 J e) None of the above