determine value of acceleration?

Question

The nominal stopping distances of a vehicle is (a) 147 ft from 60.0 mi/h. Determine the value of the acceleration, assuming that it is constant during each event. Give answer in m/s2 andThe nominal stopping distances of a the same vehicle is (b) 264 ft from 80.0 mi/h. Determine the value of the acceleration, assuming that it is constant during each event. Give answer in m/s2.

I have no idea how to do this

Answer 1

Well, you have constant acceleration, and you start at 60mph and end at 0 mph. This means your average speed while stopping is 30 mph right?

So if you went 147 feet, and your average speed was 30 mph, then you can figure out the time it took by this equation:

time = distance / speed

1 mile = 5280 feet
1 hour = 3600 seconds

speed = 30 mph = 44 ft/sec

time = 147 / 44 = 3.34 sec

Once you have time, you can figure out acceleration by this equation:

acceleration = change in speed / time

change in speed = 60 mph = 88 ft/sec

acceleration = 88 / 3.34 = 26.34 ft/sec^2

1 meter = 3.28 feet

26.34 ft/sec^2 = 8.03 m/s^2

Answer for b is 7.95 m/s^2

The hard part of these problems is converting the units.

Answer 2

OK, this is a basic mechanics problem using the formula

(final velocity)^2 = (initial velocity)^2 + 2*acceleration*distance

Vf^2 = Vi^2 + 2ad

Using this a.)= -8.02 m/s2, b.)= -7.94m/s2

Don't forget to bring the signs over. You can use common sense knowing that the object is slowing down to a halt thus a negative acceleration.

Answer 3

Constant deceleration is fine. Other 2 answers are right. The force to stop the car will vary to keep the deceleration constant

Answer 4

http://hyperphysics.phy-astr.gsu.edu/hbase/mot.html
V^2=Vo^2+2ax You know x=147 ft(need in meters). Vo=60 Mi/h (need in Meters per second), and V=0 so Acceleration = -Vo^2/2x

Answer 5

your problen is not exactly determinate.. The reason is that acceleration is a variable. a variable is not a constant.Though there is a solution to your constant acceleration problem the solution would be not exact.

Answer 6

information superhighway rigidity appearing on a body with mass m. it fairly is the only aspect. at the same time as F = ma = SUM(f) is the internet rigidity appearing on a mass m via a sum of forces, we see that when F = 0, the acceleration a = 0; at the same time as F > 0, a > 0, and at the same time as F < 0, a < 0. it is that user-friendly.