Tag: physics

A line having a total resistance of $0.5 \Omega$ delivers $15$kW at $240$ volt to a small factory. The efficiency of transmission will be :

The weight of a man is 60 kg. If ${ 10 }^{ 5 }$ cal heat is supplied from food and his efficiency is 28%. The height upto which he can climb, will be-

A crane can lift up $10,000$ kg of coal in $1$ hour from a mine of $180$m depth. If the efficiency of the crane is $60\%$, its input power must be? $(g=10ms^{-2})$

An engine pump $400$kg of water through height of $10m$ in $40s$. Find the power of the engine if its efficiency is $80\%$ (Taken $g=10ms^{-2}$).

A man of mass 80 kg carrying a load of 20 kg walks up a stair case in 20s.If the number of steps is 40 and width and height of each step are 20 cm and 15 cm respectively.The efficiency of the man is 

A carnot engine is designed to operate between $480 \, K$ and $300 \, K$. If the engine actually produce $1.2 \, J$ of mechanical energy per cal. of heat absorbed, then the ratio of actual efficiency to theoretical efficiency is

An ideal gas is taken through a cyclic thermo dynamical process through four steps. The amounts of heat involved in these steps are ${ Q } _{ 1 }=5960 J$ ,${ Q } _{ 2 }=5585 J$, ${ Q } _{ 1 }=2980$ J,${ Q } _{ 1 }=3645 J$;espectively, The corresponding works involved are ${ W } _{ 1 }=2200 J$, ${ W } _{ 1 }= -825 J$, ${ W } _{ 2 }=-1100$ J and  ${ W } _{ 4 }$  respectively. Find The value of W and efficiency of the cycle

A man of mass 60 Kg lifts a 15 Kg mass to the top of a building of height 10 m in 5 minutes. H is efficiency is

Among the following the correct expression of efficiency is 

A body of mass  $4\mathrm { kg }$  is moving up an inclined plane rising  $1$  in  $40$  with velocity  $40\mathrm { m } / \mathrm { sec }$  if efficiency is  $50\%$  the calculate power required.