Please help!! !! A car enters a freeway entrance ramp going 35 miles per hour. I
ID: 2272924 • Letter: P
Question
Please help!!!!
A car enters a freeway entrance ramp going 35 miles per hour. It accelerates at a rate of 2.11
m/s/s up the entrance ramp. When it reaches the actual freeway, the car is going 60 miles per
hour. The driver sets the cruise control at 60 mile per hour and travels for 85 miles. At the 85
mile mark he sees a sign that says that there is a Taco Bell in 2 more miles. He takes that exit,
accelerating at the same magnitude down the same size exit ramp.
a. How long (in meters) are the entrance and exit ramps?
b. How much time does the car spend on the entrance ramp? On the exit ramp?
c. How much time does the total trip take?
d. What is the total trip distance?
Explanation / Answer
a.
(v^2) = (u^2) + 2*a*s
where v = 60 mph
u = 35 mph
a = 2.11 m/s/s
and we have to find s
b.
s = u*t + 1/2(a*t*t)
we know u, s and a
hence we can find the time
c.
the driver travels at 60mph for 85 miles
therefore the total time on the freeway = 85/60 hours
time taken for the total trip = time on freeway + time on the ramps which we found in part (b)
d.
total trip distance = 85 miles + length of ramps ( which we found in part (a) )
PLEASE DO THE CHECK THE UNITS OF ACCELERATION