Assuming that’s it’s just the normal force of Earth’s gravity at work on the witch, it’s just a case of working Newton’s second backwards with the gravitational “constant” acceleration ≈ 9.8 m/s²:
F = ma
980 N = m × 9.8 m/s²
980 / 9.8 = (m × 9.8) / 9.8, units omitted for text clarity
100 kg = m
In other words, op is assuming that an average size witch masses approximately 100kg (or about 220 lbs in fingers, knees, and toes units).
What’s an average sized witch?
Assuming that’s it’s just the normal force of Earth’s gravity at work on the witch, it’s just a case of working Newton’s second backwards with the gravitational “constant” acceleration ≈ 9.8 m/s²:
F = ma
980 N = m × 9.8 m/s²
980 / 9.8 = (m × 9.8) / 9.8, units omitted for text clarity
100 kg = m
In other words, op is assuming that an average size witch masses approximately 100kg (or about 220 lbs in fingers, knees, and toes units).
That’s not enough for flight, only enough to nullify gravity. It makes sense OP would leave some trust for acceleration
They’ll flap their arms for propulsion