A car skids to a stop with a deceleration of 4.1 m/s2. Due to the hard braking, the tires leave 51 m long skid marks on the pavement.?
a) Determine the speed of the car (in m/s) just before braking.
b) How much time is required for the car to stop?
- oldschoolLv 74 weeks ago
We can use conservation of energy
a = F/m = µmg/m = µg = 4.1m/s²
The kinetic energy is consumed by friction over 51m
F*d = ½mV² = µmg*51 -----> V² = 2*µg*51 = 2*4.1*51 = 20.45²
V = 21m/s <<<< a)
b) 51 = 20.45*t - ½*a*t² at t = 5s <<<< b)