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## Work , Power and Energy Essay

**Work , Power and Energy Essay**

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Experiment

**and b.**

t (s) | t^{2 }(s^{2}) |
Y_{1} (cm) |
Y_{2} (cm) |
Y_{3} (cm) |
Y_{4} (cm) |
Y_{5} (cm) |
Y (cm) | g |

0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |

0.1 | 0.01 | 4.9 | 4.8 | 4.9 | 4.6 | 4.7 | 4.78 | 956 |

0.2 | 0.04 | 19.3 | 19.4 | 19.4 | 19.3 | 19.3 | 19.34 | 967 |

0.3 | 0.09 | 44 | 43.8 | 43.7 | 43.6 | 43.9 | 43.8 | 973.3333 |

0.4 | 0.16 | 78.3 | 78.4 | 78 | 78.1 | 77.9 | 78.14 | 976.75 |

0.5 | 0.25 | 122.1 | 122.1 | 122 | 122.5 | 122.3 | 122.2 | 977.6 |

y = 489.13x – 0.1265

slope is the coefficient of x = 489.13

slope = 489.13 = (0.5)g

Experimental value of g = __978.26 cm/s ^{2}__

**f.**

Percent error of experimental value = [(accepted value – experimental value)/accepted value] * 100

= [(980 – 978.26)/180] * 100 = [(1.74)/980] * 100 = 0.001776 * 100

Percent error = __0.1776__%

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Identify the following

**The SI units for energy and work**

__Joule (J)__

**SI unit for power that is equivalent to Joules/second**

__Watt (W)__

**Type of energy associated with the motion of an object**

__Kinetic energy__

**Type of stored energy associated with the position of an object in a gravitational field.**

__Potential energy __

**Type of stored energy associated with the configuration of an object that is stretchy or springy**

__Elastic potential energy__

**Transfer of energy that occurs when a force acts through a distance**

__Work__

**Measure of how quickly work is done or energy is transferred. Work , Power and Energy Essay.**

__1 Joule, the energy transferred when 1 Newton force is applied to move an object through a 1 meter distance. __

**The sum of the kinetic and potential energy in a system.**

__Mechanical energy__

**Level where the height and gravitational potential energy are set at zero**

__Zero level where the height does not change the kinetic energy or the potential energy. __

**Type of force that does not change the total mechanical energy of a system when it does work on it. Examples include gravitational forces, electrical forces, and spring forces. They are called as [clue: conservative or non-conservative] forces**

__Conservative forces act on the object with the work done being dependent on the object’s change in positon and the pathway taken. If the object is in a closed circuit, then the work done is zero with no mechanical energy being lost. Examples of conservative forces include spring force and gravitational force. Non-conservative forces are only dependent on the pathway that the object takes as some mechanical energy is lost from the system as it is converted into light, sound, heat and other forms of energy. Examples of non-conservative forces include air resistance, pull and push, drag forces and friction. __

**ASSIGNMENT 5: WORK, POWER, ENERGY [Chapter 3]**

**IDENTIFY THE FOLLOWING**

- The SI units for energy and work
- SI unit for power that is equivalent to Joules/second
- Type of energy associated with the motion of an object
- Type of stored energy associated with the position of an object in a gravitational field. Work , Power and Energy Essay. 5. Type of stored energy associated with the configuration of an object that is stretchy or springy
- Transfer of energy that occurs when a force acts through a distance
- Measure of how quickly work is done or energy is transferred.
- The sum of the kinetic and potential energy in a system.
- Level where the height and gravitational potential energy are set at zero
- Type of force that does not change the total mechanical energy of a system when it does work on it. Examples include gravitational forces, electrical forces, and spring forces. They are called as [clue: conservative or non-conservative] forces

TRUE /FALSE

11.Type of a force that adds or removes energy from a system when it does work. Examples include frictional forces, air resistance, and applied forces

- Energy can be converted to different forms or transferred to different places but the total amount of energy does not change.
- A force acting in the direction an object is moving does positive work.
- Kinetic energy is a vector quantity.
- The gravitational potential energy of a moving object is always zero.
- When mechanical energy is conserved, the kinetic energy you end up with always equals the gravitational potential energy you start with.
- A force acting perpendicular to an object’s displacement does negative work
- Energy can be converted from one form to another form.
- The force needed to lift an object at a constant speed is equal to the weight of the object.
- Centripetal forces do zero work on an object.
- The harder you push on a wall the more work you do.
- Doing the same amount of work in less time requires a greater power output
- The SI units of power, watts, are equivalent to joules times seconds.
- The SI units of energy, joules, are equivalent to newtons times meters

** Straight forward calculations. Express answer with appropriate unit**

- How much kinetic energy does a 5.0 kg object have when it is moving at 3.0 m/s?

K = ½ mV^{2}

- How much does the gravitational potential energy of a 1.2 kg textbook increase if you lift it upward 32 cm?

PE = mgh 32 cm =0.32 m, g = 9.8 m/s^{2}

- How long must a 12 W compact fluorescent light bulb be turned on t o convert 18 kJ of electrical energy into light energy? Work , Power and Energy Essay.

E = Pt, t = E/P

- How much work is done by you when you lift a 9.0 kg object 0.50 meters off of the ground? W = mgh g =9.8 m/s
^{2}

- What power output is required of a motor that needs to lift a 450 kg elevator car 12 meters in 8.0 seconds? P = F.v, F = mg, v = d/t

- How long does it take a motor with an output of 8.0 W to lift a 2.0 kg object 88 cm? 2.2 s V = d/t 88 cm =0.88m, E= K = ½ mv
^{2}

E = Pt, t = E/P

Essay type question

**Describe in detail various forms and sources of energy. How do you conserve energy to save earth . **Work , Power and Energy Essay.