# Acceleration due to gravity

## Main Question or Discussion Point

Hello, i'm currently doing some work on the above and have ran into a problem when calculating the Time squared part as it should be in Seconds squared.

I currently have the time in miliseconds, so say I have

150ms should I square this number then convert it into seconds or convert it first and then square it.

For example 150ms the first way gives 22500 which is 22.5s

Converting it to 0.150s then squaring it gives 0.0225?

Thanks

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Doc Al
Mentor
(150ms)2 = (0.150s)2 = (0.150)2(s)2 = 0.0225 s2

Or:
(150ms)2 = (150)2(ms)2 = (150)2(0.001 s)2 = 0.0225 s2

Key point:
1 (ms)2 = 10-6 s2

I appreciate your help but i'm still puzzled by this.

Doc Al
Mentor
I appreciate your help but i'm still puzzled by this.
What part puzzles you?

Doc Al
Mentor
I'll try again:
I currently have the time in miliseconds, so say I have

150ms should I square this number then convert it into seconds or convert it first and then square it.
Whatever you do, you must square both the number and the units.

For example 150ms the first way gives 22500 which is 22.5s
No. When you square 150 ms you end up with 22500 ms2 (not just ms). You'd have to convert from ms2 to s2, which means multiplying by 10-6.

Converting it to 0.150s then squaring it gives 0.0225?
That's fine. Notice that your units are s2.

Personally, I would always convert to standard units before doing any calculations. So I would convert 150 ms to 0.150 s, and then I'd do my squaring.