Shortcut Methods

Numerical on Potential and Potential energy:


  1. Work Done:

W=F×d where

  • W = work done (in joules)
  • F = force applied (in newtons)
  • d = displacement (in meters)

In this case, the force is 5 N and the displacement is 20 m, so the work done is: W=5 N×20 m=100 J Therefore, the work done on the particle is 100 J.


  1. Potential Energy (Spring):

PE=(1/2)kx2 where,

  • PE = potential energy (in joules)
  • k = spring constant (in newtons per meter)
  • x = displacement from the relaxed position (in meters)

Here, k= 100 N/m, and x= 0.1 m (10 cm). PE=(1/2)×100 N/m×(0.1 m)2=0.5 J Therefore, the potential energy stored in the spring is 0.5 J.


  1. Potential Energy (Gravitational):

PE=mgh where

  • PE = potential energy (in joules)
  • m = mass (in kilograms)
  • g = acceleration due to gravity (9.8 m/s²)
  • h = height (in meters)

Here, m is 5 kg, g= 9.8 m/s² and h is 10 m: PE=5 kg×9.8 m/s2×10 m=490 J Therefore, the potential energy gained by the block is 490 J.


  1. Gravitational Potential Energy:

PE=mgh

Here, m= 20 kg, g= 9.8 m/s² and h= 10 m. PE=20 kg×9.8 m/s2×10 m=1960 J Therefore, the gravitational potential energy of the object is 1960 J.


  1. Kinetic Energy:

KE=1/2mv2 where

  • KE = kinetic energy (in joules)
  • m = mass (in kilograms)
  • v = velocity (in meters per second).

Here, m= 10 kg and v= 10 m/s: KE=(1/2)×10 kg×(10 m/s)2=500 J

Therefore, the kinetic energy of the block is 500 J.