i worked it out with an arbitrary track length = 2mi (more nascar like than 90mi) and:
90mph(2mi^-1) = 1/45hr
Xmph(2mi^-1) = 2/Xhr
180 = 4/((1/45) + (2/X))
X = 360/(4-4)
so am i to understand that is impossible for the car to avg 180mph (get div by 0 with track length = 90mi too...
a multiple choice question from one of my tests:
A race car covers the first lap of a two lap race with an average speed of 90mi/hr. With what speed must the driver average for the second lap so that the average speed for the two laps is 180mi/hr?
A)90mi/hr
B)180mi/hr
C)270mi/hr...
sitting here looking at my post and my physics book it dawned on me to use this eqn:
() = subscript
x(f) = x(i) + v(xi)t + 1/2 a(x)t^2
therefore
30 = 0 +v(1.50) + 1/2(-9.80)(1.50^2)
v = 27.35m/s
but that can't be, so i switched the accel to positive and got v = 12.65m/s which sounds...
need help finding where to start,
"A freely falling object requires 1.50sec to travel the last 30.0m before it hits the ground. From what height above the ground did it fall?"
I know that:
accel = -9.80m/s^2
avg. veloc for last 1.50 sec = 20m/s
that i need the initial velocity for...