Often approximated to 10 m/s-2, g is the “acceleration of a mass falling without resistance under gravity”. But if the mass is not falling, it’s because the force stopping it is equal to g times the mass – it’s the weight of the object . . .
Hi, there! I’m g. To keep up with me
You’d better not procrastinate:
10 metres per second per second, it’s reckoned,
Is how you must accelerate.
(That’s not quite exact. My value, in fact
Isn’t constant, but varies with place:
Though 9.81 is the number for some,
You really should check – just in case.)