Work,Energy and Momentum

Work,Energy and Momentum

1. Formulae

   • Gravitational potential energy and kinetic energy
     • Ep=mgh [E (gravitational potential(J)=Mass(G)*Gravity (NKG)*height(m)]
     • Ek=1/2mv^2 [Ek(kinetic energy(J)=1/2*mass(g)*speed^2(m/s)]
     • GPE=mass*change in height *gravitational field strength (GPE=kg*metres*N/kg)
   • Work and energy
     • W=F*D [Work done(J) = Force applied(N) * Distance (M)]
     • P= E/t [Power (w)=Energy transferred(J)/Time (s)
     • Power=Work done / time taken [W =(J)/(S)]
       • Power is the rate energy is transferred
   • Momentum/change in momentum
     • Momentum=mass * velocity [kg m/s =kg * m/s]
     • Force =change in momentum/time [N=kg m/s / s]
   • Gravity= 9.81 /10 N / kg
   • Weight = Mass * Gravitational field strength. (N=KG* N/Kg)

2. Key information

   • Work done=energy transferred. Units of work(J)=units for energy (J)
   • Crumple zones (example in the real world)
     • A feature that is implemented in vehicles that creates a safe zone for a vehicle upon impact. The zone crumples on impact increasing the impact time and decreasing the force preoduced by the change in momentum.
       • There are other features of a vehicle that aids the passenger upon impact.These could be : side impact bars , seat belts and air bags.
   • All objects that move have momentum. The momentum can be linked to mass and velocity.
   • Momentum is conserved, value cancels out to 0 kg m/s. Equals to starting momentum. As long as there is no other external force act on it.
     • Total momentum before collision = Total momentum after collision
   • Representations

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