Question

calculate the work done required to stop a car of mass 50 kg moving witha velocity of 54 km/hh​

Answer 1

Refer to the attachment..

Answer 2

$According to Work Energy Theorem:− \\ \\ \begin{gathered}\sf:\implies\pink{ Work \ Done = \Delta Energy_{Kinetic\ energy } }\\\\\sf:\implies Work \ Done = \dfrac{1}{2}mv^2- \dfrac{1}{2}mu^2 \\\\\sf:\implies Work \ Done = \dfrac{1}{2}m ( v^2 - u^2 ) \\\\\sf:\implies Work \ Done = \dfrac{1}{2}\times 50kg [ (0m/s)^2 - (54km/hr)^2 ] \\\\\sf:\implies Work \ Done = 25kg \bigg\lgroup 0m^2/s^2 - \bigg(54 \times \dfrac{5}{18}m/s.\bigg)^2 \bigg\rgroup \\\\\sf:\implies Work \ Done = 25kg [ 0m^2/s^2 - (15m/s)^2 ] \\\\\sf:\implies Work \ Done = 25kg \times - 225 m^2/s^2 \\\\\mathfrak:\implies \boxed{\pink{\mathfrak {Work \ Done = -5625 \ Joules .} }}\end{gathered}$