Physics/mechanics type question

[dim_sim]

Wooh, first post! 
Anyway, I'm having trouble with this question.. possibly because I'm not doing physics. D:

A person slides down a vertical rope. At first, they are accelerating at 4.9 m/s^2 and the tension in the rope is 25kgwt. They then continue at a uniform speed and then decelerate and 4.9 m/s^2. Find the mass of the person and the tension in the rope in the latter two stages.
Thanks!

[Rectophobia]

Not sure if a response this late will be of any help, but here goes nothing.
(I wouldn't put too much money on my answer being right btw)

To work out the mass of the person, you have to realise that their acceleration is exactly half of what it should be under the force of gravity. As such, assuming that air resistance is negligible, the tension in the rope would have to be half of the mass of the person.

=> mass of person
= 2*tension of rope
= 2*25kgwt
= 50kgwt

For the second part, you can use the information you were initially given and the mass that we now know.
You're told that they decelerate at 4.9ms^-2, so the magnitude of the tension of the rope will have to be 25kgwt greater than the force of gravity acting on the person (5okgwt). From this you can conclude that the   |tension force| - |gravitational force| = 25kgwt,
=> Tension - 50kgwt = 25kgwt
=> Tension = 75kgwt