In a test carried by a car manufacturer, a test driver is asked to put on his brakes when a warning light is suddenly flashed. When traveling 25 m/s the driver is able to stop in 50 m after slamming on the breaks. a. What is the car's acceleration?
Please show/explain all work. Please show what formulas were used.
2007-12-14 09:37:41 · 2 answers · asked by Kantilal P 1 in Science & Mathematics ➔ Physics
b. If the car has a mass of 1200 kg, what is the breaking force?
2007-12-14 09:38:25 · update #1
let's use equations of motion:
Position
50=25*t-.5*a*t^2
Speed
0=25-a*t
solve first for t
then for a
t=4
a=25/4
a=6.25
Using F=m*a
F=1200*6.25
F=7500 N
j
2007-12-14 09:44:12 · answer #1 · answered by odu83 7 · 0⤊ 1⤋
Making the obviosly invalid assumption that the driver's reaction time is zero, we have the average speed is 12.5 m/sec, so 50/12.5 = 4 seconds are required to stop, and the acceleration is -25/4 m/sec^2.
2007-12-14 10:15:04 · answer #2 · answered by Anonymous · 0⤊ 1⤋