2.10 : WORK, ENERGY, POWER AND EFFICIENCY

Slides:



Advertisements
Similar presentations
Work, Energy & Power Honors Physics. There are many different TYPES of Energy. Energy is expressed in JOULES (J) 4.19 J = 1 calorie Energy can be expressed.
Advertisements

Work, Energy, And Power m Honors Physics Lecture Notes.
Energy Conversion of Energy Forms of Energy Energy Work.
Work, Energy, and Power Samar Hathout KDTH 101. Work is the transfer of energy through motion. In order for work to take place, a force must be exerted.
Mechanical Kinetic, Potential (gravitational, elastic) Thermal Chemical Electromagnetic Nuclear Forms of Energy Energy is conserved!
Work Work,W applied force,F displacement of an object in the direction of the applied force,s. Work,W is defined as the product of the applied force,F.
Regents Physics Work and Energy.
Work, power and energy(2)
2.1d Mechanics Work, energy and power Breithaupt pages 148 to 159 April 14 th, 2012.
1© Manhattan Press (H.K.) Ltd. Work Energy Energy 3.6 Work, energy and power Power Power.
Chapter 4 Work & Energy Dr. Ali.
ENERGY Part I.
Chapter 5 – Work and Energy If an object is moved by a force and the force and displacement are in the same direction, then work equals the product of.

The Work Energy Theorem Up to this point we have learned Kinematics and Newton's Laws. Let 's see what happens when we apply BOTH to our new formula for.
College Physics, 7th Edition
IGCSE Coordinate Science 1 P3: Energy, Work, and Power Unit 7 – part 1.
Regents Physics Work and Energy. Energy and Work Energy is the ability to Work Work is the transfer of energy to an object, or transformation of energy.
Chapter 5 Work and Energy. 6-1 Work Done by a Constant Force The work done by a constant force is defined as the distance moved multiplied by the component.
Mechanics Work and Energy Chapter 6 Work  What is “work”?  Work is done when a force moves an object some distance  The force (or a component of the.
Energy m m Physics 2053 Lecture Notes Energy.
Physics 3.3. Work WWWWork is defined as Force in the direction of motion x the distance moved. WWWWork is also defined as the change in total.
Chapter 6 Work, Energy, Power.
Chapter 10 & 11 Energy & Work. Energy The capacity of a physical system to perform work. Can be heat, kinetic or mechanical energy, light, potential energy,
Units: 1Newton . 1 meter = 1 joule = 1J
Work and Energy. Work, Power, & Energy Energy offers an alternative analysis of motion and its causes. Energy is transformed from 1 type to another in.
Work and Energy.
Mechanics Topic 2.3 Work, Energy and Power. Work A simple definition of work is the force multiplied by the distance moved However this does not take.
1 Work When a force moves something, work is done. Whenever work is done, energy is changed into a different form. Chemical energy → Kinetic energy.
Energy and work Sections 12, 13, 14 and 15
Energy, Work & Power: Types of Energy The following are some examples of types of energy: Internal energy Gravitational potential energy = mgh Kinetic.
Work and Energy Level 1 Physics. OBJECTIVES AND ESSENTIAL QUESTIONS OBJECTIVES Define and apply the concepts of work done by a constant force, potential.
Work effect of force on the displacement of the object can be computed by multiplying the force by the parallel displacement force X displacement (assuming.
Work and Energy.
WORK, ENERGY AND POWER WHY ARE WE WORKING SO HARD?
CHAPTER - 11 WORK AND ENERGY CLASS :- IX. 1) Work :- Work is said to be done when a force acts on an object and the object is displaced in the direction.
JR/2008 Work & Energy If an object moves due to the action of an applied force the force is said to have done WORK on the object. Work is the product of.
Chapter 5: Work and Energy. Today’s Objectives What do you think? List five examples of things you have done in the last year that you would consider.
WORK A force that causes a displacement of an object does work on the object. W = F d Work is done –if the object the work is done on moves due to the.
Work and Energy. Work… …is the product of the magnitude of displacement times the component of force parallel to the displacement. W = F ‖ d Units: N.
Alta Conceptual Physics Energy Chapter 8. Alta Conceptual Physics Energy Facts There are different types of energy Energy of all types is measured in.
Work and Kinetic Energy. What is kinetic energy?  If an object is moving, it has energy. You can think of kinetic energy as the energy of motion, and.
Understanding Work, Energy,
Pre-AP Physics.  Energy is expressed in JOULES (J)  4.19 J = 1 calorie  Energy can be expressed more specifically by using the term WORK(W) Work =
Work, Energy and Power Energy (Joule) Ability to do work. Law of Conservation of Energy: Energy cannot be destroyed nor created but is converted from.
 Work  Energy  Kinetic Energy  Potential Energy  Mechanical Energy  Conservation of Mechanical Energy.
Chapter 5 Work and Energy. Mechanical Energy  Mechanical Energy is the energy that an object has due to its motion or its position.  Two kinds of mechanical.
Ch.5 Energy Energy comes in various forms:. When you apply a Force to an object and it moves a displacement (x), then you get done. i.e.(Weight is now.
Energy Notes Energy is one of the most important concepts in science. An object has energy if it can produce a change in itself or in its surroundings.
Energy, Work and Power. Work, Energy and Power Objectives: Describe the relationship between work and energy Calculate the work done by a constant applied.
Work, Power, and Energy. WORK  In Physics, work has a very specific definition.  This is not work in Physics.
Work is only done by a force on an object if the force causes the object to move in the direction of the force. Objects that are at rest may have many.
EnergyDefinitions 1 Different kinds of energy Kinetic energy Kinetic energy is motion energy. The faster it moves the more kinetic energy it possesses.
Work, Energy & Power PreAP Physics. There are many different TYPES of Energy. Energy is expressed in JOULES (J) 4.19 J = 1 calorie Energy can be expressed.
Unit 5: Work, Power and Energy. Work Work is done when a force causes a change in motion of an object, or work is a force that is applied to an object.
Work, Energy & Power Honors Physics. There are many different TYPES of Energy. Energy is expressed in JOULES (J) 4.19 J = 1 calorie Energy can be expressed.
Work and Energy.
Work, Energy & Power AP Physics 1.
General Physics 101 PHYS Dr. Zyad Ahmed Tawfik
Unit 10 Work, Power, & Energy.
Work, Energy and Power Chapter 11.
Work.
Work and Energy.
POWER ENERGY WORK WHEN ENERGY IS TRANSFORMED FROM ONE FORM TO ANOTHER WORK IS DONE WHEN ? WHEN ? WHEN ENERGY IS TRANSFORMED FROM ONE FORM.
Work, Energy and Power.
Work, Energy & Power Honors Physics.
Work, Energy & Power Physics.
Work, Energy, Power.
Work, energy and power.
Presentation transcript:

2.10 : WORK, ENERGY, POWER AND EFFICIENCY FORCE AND MOTION

WORK Is defined as the product of the applied force and the distance moved in the direction of the force. Work = force x distance W = F x s SI unit is the Joule (J) Is a scalar quantity

No work done when: A force is applied but no displacement occurs. An object undergoes a displacement with no applied force acting on it. The direction of motion is perpendicular to the applied force.

3 SITUATION THAT INVOLVE WORK Direction of force, F is same as the direction of displacement, s. W = F x s F s F

Direction of force, F is not same as the direction of displacement, s. W = F cos θ x s W = F s cos θ F s F θ θ F cos θ

Direction of force, F is perpendicular to the direction of displacement, s. W = F x s W = F cos 90° x s W = 0 F s F

Example 1 If a box is pushed with a force of 40 N and it moves steadily through a distance of 3m in the direction of the force, calculate the work done. Answer: W = 120 J

Example 2 A women pulls a suitcase with a force of 25 N at an angle of 60° with the horizontal. What is the work done by the women if the suitcase moves a distance of 8 m along the floor? Answer,: W = 100 J

FORCE–DISTANCE GRAPH Area under a force–distance graph = work done. Work = F x s = a x b Force, F a Distance, s b

WORK DONE AGAINST THE FORCE OF GRAVITY An upward force, F is applied to lift the object of weight, W to a height, h. W = F x h W = mgh F h W

ENERGY Is defined as potential or the ability to do work. Form energy: Gravitational potential energy Kinetic energy Heat energy Sound energy Electrical energy SI unit in Joule, J and it scalar quantity. Energy is transferred from 1 object to another when work is done.

KINETIC ENERGY, Ek Is a energy possessed by a moving object. It scalar quantity. SI unit in Joules, J. Formula : Ek = 1 mv2 2 Ek = 1(mv2) – 1(mu2) 2 2 Object moving from initial velocity to final velocity

POTENTIAL ENERGY, Ep Defined as energy of an object due to its higher position in the gravitational field. Depend on mass, gravitational field and height. Formula: Ep = mgh # m = mass # g = acceleration due to gravity # h = difference between height

Example 3 In a school sports event, a student of mass 40 kg runs past the finishing line with a velocity of 7 ms-1. Calculate his kinetic energy. Answer: Ek = 980 J

Example 4 A durian fruit hanging from its branch has gravitational potential energy due to its higher position above the ground. The mass of the fruit is 2.5 kg and it hangs 3 m above the ground. What is the gravitational potential energy of the fruit? (g = 10 ms-2) Answer: Ep = 75 J

PRINCIPLE OF CONSERVATION OF ENERGY State that energy cannot be created or destroyed. It can be transformed from one form to another. The total energy in a system is constant. This means there is no energy gained or lost in a process. Formula : mgh = 1mv2 2

Example: On winning a match, a tennis player hits a tennis ball vertically upward with an initial velocity of 25ms-1. What is the maximum height attained by the ball? (g = 10ms-2) Answer ; h = 31.25 m

POWER Is the rate at which work is done or rate at which energy is transformed. Formula; Power, P = work done @ energy transformed time taken time taken P = W @ F x s @ F x s @ Fv t t t P = E t SI unit is watt (W) or Js-1 Is scalar quantity P ∞ W if t constant P ∞ 1 / t if work constant

Example: A weightlifter lifts 160kg of weights from the floor to a height of 2m above his head in a time of 0.8s. What is the power generated by the weightlifter during this time? (g = 10ms-2) Answer : P = 4000 W

EFFICIENCY The percentage of the input energy that is transformed to useful form of output energy. Formula : efficiency = useful energy output x 100% energy input = Eo x 100% Ei

Also can be calculated in terms of power. efficiency = useful power output x 100% power input = Po x 100% Pi

Example: An electric motor in a toy crane can lift a 0.12 kg weight through a height of 0.4m in 5s. During this time, the batteries supply 0.80 J of energy to the motor. Calculate The useful energy output of the motor The efficiency of the motor Answer: Eo = 0.48J Efficiency = 60 %

Exercise A steel ball of mass 2 kg is released from a height of 8 m from the ground. On hitting the ground, the ball rebounds to a height of 3.2 m as shown in figure. If air resistance can be neglected and the acceleration due to gravity g = 10 ms-2, find The kinetic energy of the ball before it reaches the ground. The velocity of the ball on reaching the ground. The kinetic energy of the ball as it leaves the ground on rebound. The velocity of the ball on rebound. 8 m 3.2 m Ek =160 J v1 = 12.65 ms-1 Ek = 64 J v2 = 8 ms-1

Exercise A car moves at a constant velocity of 72 kmj-1. Find the power generated by the car if the force of friction that acts on it is 1500 N. Answer : P = 30000 W