Question

A 90000 lbs truck is braked to a stop in 95 ft. from an initial speed of 95 ft/s . How

much force was required ?

Answer 1

Newton motion 3rd law

$v^2=u^2+2as$

$0=95^2+2\times95\times a$

$a=\frac{-95}{2}=-47.5ft/sec^2$

W=mg

$m=\frac{90000}{32.2}=2795.03$ pound

Force =ma

$$F=2795.03\times47.5=132763.97lb ft/sec^2$$