Basic Physics Question: 10 m/s^2 Why the second square?

Question

Free Fall Acceleration = 10 m/s^2

My book says:
"The unit of time , the second, enters twice. One for the unit of speed and again for the time interval during which the speed changes"

My question is:
I throw a ball up there in the air at 30 m/s, each second the ball decreases it speed and goes 20 m/s then 10 m/s and then 0 m/s then if i am measuring this with only one "s" , why do i have "s^2"?? where is the other second comming from?? or what is the other second measuring? 10 m/s^2 = 10 m/ sxs (i know one "s" measures my seconds and the other the interval??? what do they mean by that????)

Answer 1

In each second the ball decreases by an amount 10m/s.

Hence the acceleration is 10 m/s in one second or 10m/s per second.

You see second comes twice.



acceleration = [final speed - initial speed ] / time.



Let the final speed be 20m/s and initial speed be 60m/s.

this change takes place in 4 second.



In 4 second the change is 60 - 40 = 20 m/s.



In one second the change is [20 m/s] divided by 4 second



i.e 5 [m/s] per second or 5 [m/s ] / second = 5 m/s^2.

Answer 2

Acceleration is defined by

a = (v - u)/t = change in velocity/time taken

The units are (m/s)/s = m/s^2 or ms^-2

Answer 3

acceleration is the fee of substitute of speed from definition: speed =displacement /time taken considering fee of substitute of speed =speed /time taken displacement /time * a million/ time the units are m/s2

Answer 4

squared second means ACCELERATION



s^1 means SPEED



ACCELERATION it means change of SPEED with time..