Power(Work,Power,Energy)

Applications of power :

4)The car moves on a rough horizontal road with a constant speed 'V' then the instaneous power of engine is
P = F.V (V constant)  
 But F = f 
P = fV (Here f = frictional force on rough  horizontal surface)  P =\(\mu\) mg. V

5)A body of mass 'm' is initially at rest. By the application of constant force its velocity changes to "V₀" in time ' t₀' then
\(\begin{gathered} v = u + at \hfill \\ {v_0} = a{t_0} \hfill \\ \end{gathered} \)     
acceleration of the body is  \(a\, = \,\frac{{{v_0}}}{{{t_0}}}\)

a)Find instantaneous power at an instant of time 't' is 
P = F.V = (ma) (at) = m a² t 
\({P_{\operatorname{in} st}} = m{\left( {\frac{{{v_0}}}{{{t_0}}}} \right)^2}t\)
 b)Average power during the time 't' is
P_av = \(\frac{1}{2}.{p_{inst}}\,\) ;