Work and energy, Physics

WORK AND ENERGY

 

1.  Work can be defined as: the force applied in direction of displacement ×.  This means that if the force F acts at an angle θ with respect to the direction of motion, then 

      →   →

W = F ⋅ d = Fd cosθ

1233_work energy.png

2.  a) Work is the scalar quantity - it has magnitude but no direction.

b) The dimensions of the  work are: M × (L T -2 ) × =  M L2T -2

 

c) The units: 1 Newton × 1 Metre =  1 Joule (J)

 

3.  Suppose you lift the mass of 20 kg from a distance of 2 metres. Afterwards the work you perform is 20 kg × 9.8 Newtons × 2 metres  = 39.2 Joules. Conversely, the force of gravity is directed opposite to the force exerted by you and the work done by gravity is - 39.2 Joules.

 

4. What if the force differs with distance (as we pull the spring harder as it becomes longer). In such case, we should break up distance over which the force acts into small parts so that the force is approximately constant over each bit. As we create the pieces smaller and smaller, we will attain the exact result:

0

90_work energy2.png

Now add up all the little pieces of work:

1863_work energy1.png

To get the exact result let Δx → 0 and the number of intervals N

7.  Energy is the capacity of a physical system to perform work:

?    it comes in various forms - mechanical, nuclear, chemical, electrical,  etc

1)   it can be stored

2)   it can be converted into different forms

3)    it can never be created or destroyed

Posted Date: 7/26/2012 2:42:56 AM | Location : United States







Related Discussions:- Work and energy, Assignment Help, Ask Question on Work and energy, Get Answer, Expert's Help, Work and energy Discussions

Write discussion on Work and energy
Your posts are moderated
Related Questions
A 985-kg car travelling south at 29.0 m/s hits a truck travelling  18.0 m/s west, as shown in the figure below. After the collision, the vehicles stick together and travel with

describe the construction and working of michelson interformeter?

COHERENCE : 1) Visible light energy is emitted when the excited electrons in atoms undergo transitions to the ground state. 2) In ordinary light sources, these transitions

Historical development of atomic models In olden days there was an idea that all matter is made of tiny indivisible particles. When Thomson discovered electron, this idea

The charge and discharge characteristics of lead battery: During discharge the plates are converted into lead sulphate, the water content of the electrolyte increases, the inte

Demerits of Vacuum Diode over Semiconductor Diode (i)  Bigger in size (ii)  Less efficiency (iii)  Expensive

With the help of a bb diagram, define the principle of an optical communication system. Give its two advantages over cable communication system

According to Hooke's law, within elastic limit,  stress  strain or            stress  = E Χ strain              or    Stress / Strain= E = a constant, Where E is called a

What are non ohmic and ohmic devices? Give examples The manganin wire is used in the manufacturing of standard resistances. Why?

Show that the Nusselt number for a sphere in a quiescent fluid is 2. Hint: Write the thermal resistance for the outer surface of the sphere in terms as both conductive and conve