Work (Work-Power-Energy)

CDF POINTS

1. The amount of work done is measured by the dot product of force and displacement.so it is a scalar
2.    \( W = \overline F .\overline S = FSCos\theta \)
3.  Erg in CGS system, joule  in S I system  one joule   =10⁷ erg     
4.  Work done is positive if the force or it’s component is along the direction of the displacement
5.  Work done is netive if the force or it’s component is in opposite to the direction of the displacement
6.  Work done is zero if the force or it’s component is perpendicular to the direction of the displacement
7.  Work done is independent of time
8.  The area of force and displacement graph gives work.
9.  A uniform rod of mass m and length is suspended vertically. If it is lifted to a side till it makes an angle to the vertical , work done  against gravity is   \( \text{W} = \frac{{\text{mgl}}} {\text{2}}\text{(1} - \text{Cos}\theta \text{)} \) 
10  A point sized sphere of mass m is suspended vertically using a string of length l . If the bob is pulled to a side till the string makes an angle \(\theta\) with the vertical, work done against  gravity is  \( W = mgl(1 - Cos\theta ) \)
11.A uniform chain of mass m and length ‘l’ is kept on a table such that \(\frac {1} {n}th\) of  its length ishanging down vertically from the edge of the table. The work done against gravity to pull the hanging part on to the table is \( W = \frac{{mgl}} {{2n^2 }} \)