Work Power Energy

Work Power Energy: W =  Work done by variable force W = dw =  Work done against friction on a level surface W = F × S =  mgs ('' is coefficient of friction)  The work done in lifting a body of mass m having density inside a liquid of density through a height h is (a = 0) W = mgh Work done in stretching or compressing a spring is .  Work done by the tension in the rope is W = m(g + a)h  Electrostatic P.E =  P.E = mgh  K.E = .  Work energy theorem W =  If p is linear momentum of a body moving with kinetic energy E, we can write E = .  A bullet of mass m moving with velocity v stops in wooden block after penetrating through a distance x. If F is resistance offered by the block to the bullet, then F = or v2  x  A sphere of mass m is dropped from a height 'h' above the ground. On reaching the ground, it pierces through a distance S and then stops finally. Resistance offered by the ground is R. Then R = mg Time of penetration is t =  Velocity of bullet v =  P =  If a machine gun fires n bullets per second such that mass of each bullet is m and coming out with velocity v, power of that machine gun  If a pump/crane is used to lift water/coal of mass m to a height h in time 't' power of that pump or crane is p =  If efficiency of that crane or motor is  %, then Power of engine p = mgv.