Question

A car is moving with a velocity of 72km/h. By applying brakes a negative acceleration of 0.4m/s2 is produced. the distance covered by the car before it stops?

Answer 1

The initial velocity is
`v_0=72~km/h=20~m/s`. Using the Torricelli's Equation:


`v^2=v_0^2+2a\Delta S\Longrightarrow 0=20^2+2\cdot(-0.4)\Delta S\iff\\\\ 0.8\Delta S=400\iff \Delta S=(400)/(0.8)\iff\boxed{\Delta S=500~m}`