Frazer does Physics: 4.12 Kinetic Energy

October 4, 2011

Recall and use the relationship:

$Kinetic\, Energy=\frac{mass\times velocity^{2}}{2}$

$KE=\frac{mv^{2}}{2}$

KE = Kinetic energy [Joules, J]

m = mass [Kilograms, kg]

v = velocity [metres per second, m/s]

Using the formula…

Calculate the Kinetic Energy of a 10 tonne lorry driving along the expressway at 100km/hr
(NB: 1 tonne = 1000kg; 1km/hr = 0.28m/s)

$KE=\frac{mv^{2}}{2}$

$KE=\frac{10,000\times 28^{2}}{2}$
$KE=3,920,000J\: or\: 3,920kJ\: or\: 3.92MJ$