# Gravity acceleration - why is it inverse time squared?

I've looked up and understand the reason behind the number of the acceleration of gravity $(9.8)$. But whenever people describe it they say it's $9.8 \text{m/s}^2$.

I don't understand why it's inverse time squared, why isn't it just a number like $9.8 \text{m/s}$?

• By the way, it's not $(\frac m s )^2$, it's $\frac m {s^2}$; which may be part of the confusion by the sounds of it. – JMac Jul 4 '17 at 23:08
• Acceleration is the rate of change of speed, that is how fast does the speed change per unit of time. In the case of gravity it is changing at 9.8 meters per second every second. As an example, initially at speed = 0 m/s, at t=1 second it is 9.8 m/s, at t=2 seconds it is 2x9.8 m/s=19.6 m/s etc. – nluigi Jul 5 '17 at 8:11

As any ordinary acceleration, the quantity $9.8\, \mathrm{m/s^2}$ means that the velocity increases by $9.8$ meters per second, each second. Hence $9.8$ meters per second, per second.
$$\frac{\Delta v }{ \Delta t},$$
The unit for velocity is $m/s$. The unit for time is $s$. Hence, the units for acceleration are $m/s/s = m/s^2.$