Algbra- a hard one to understand?

Question

The acceleration of an object ( in feet per second) is given by the equation ... a= s2 – s1 .... ok now there should be a line underneath those numbers then a t below the line ...how ever i dont know how to make that line , also in the book the s's are slightly above the #'s and the #'s are small. t is the time in seconds , s2 is the speed at the end of the time, and s1 is the speed at the beginning of the time. What is the acceleration of the car that brakes from a speed of 114 feet per second to a speed of 18 feet per second in 6 seconds?

Answer 1

ahhh...
S1 means like it is the First recorded speed
==> like Speed no. 1

S2 is the speed at the end.. or the 2nd recorded speed..
===> or you may call it,, er.. speed no. 2

A= (S2 -S1)/t

here..
S1= 114 feet/sec ( for this is the speed at the start of the time)
S2= 18 feet/sec ( this is the speed at the end of time)
t= 6 seconds

substitute

a= (18-114)/6
a= -16 feet per second squared

why is it negative?
because the car is decelerating. It is slowing down . so The acceleration is negative.

acceleration is positive when the car is going faster.

why is the unit " feet per second squared"?

from the equation.. notice the units....
a= (Feet/ second)/second
a= feet / second squared

Answer 2

Acceleration=16

A=Final Velocity-Starting Velocity
Time

A=114-18/6 A=96/6

A=16

Answer 3

Not really hard to understand at all, the car is braking, so it will be deceleration or negative acceleration. Just plug in the numbers. a=(s2-s1)/t=(18-114)/6=(-96)/6= -16 feet per second

Answer 4

Ok, that's not that difficult :

acceleration = s2' - s1' / t

That's the way to draw the line, then :

s1' and s2' means that it's the first derivative of the position relative to time.

s1 = position, then

s1' = speed >>> first derivative.

then :

a = s2' - s1' / t

s2' = 18 ft/s

s1' = 114 ft/s

t = 6 seconds

a = 18 - 114 / 6 = -16 ft/s^2

It's a desacceleration, remember the sign.

Ok, that's it, hope it helps.

Answer 5

(final speed - initial speed) / time =

(18-114)/6 = (-96)/6 = -16 f/s/s

meaning that for every second that passes (during the acceleration period), the car's velocity decreases by 16 feet per second

Answer 6

a = (s2 - s1) / t

= (18 - 114) / 6

= - 96 / 6

= - 16 ft/sec^2

The negative sign means deceleration.

Answer 7

Acceleration units are usually m/s^2 when using the metric system, or ft/s^2 if a foot is your measure unit.
s1 and s2 are speeds, so they are given in ft/s
Divide the difference by t in order to get the acceleration:

a = (s2 - s1)/t

Now, to your question:
s1 = 114 ft/s
s2 = 18ft/s
t=6s

a=(18ft/s - 114ft/s)/6s = -(96ft/s)/(6s) = -16ft/s^2