A body starts from rest and falls through a height of 19.6m.what time does it take to fall through the last 4.9m. Of its fall?

Gravity = 9.8m/s can you take it from there?

There are two methods available to such a problem that I know. One of which my teacher disagrees for it is too long: finding the time it takes to cover 19.6m and (19.6+4.9)m and the time difference.

The one he advises us to do is to find the speed of the body after falling 19.6m. Then use the formula:

s=ut+\frac{1}{2}at^2

and solving for t.

Hope it helped you thinking a little more about it. :)

First find how long it takes to fall the entire distance. Then find how long it takes to fall the first 19.6 m. Subtract the 19.6 time from the total.
Equation to use: delta(x)=v(initial)*t+.5*a*(t^2)

Looks like a possible quadratic.