Variable mass of a toboggan down a slope

[karnten07]

1. Homework Statement

a 5.4kg toboggan carrying 35kg of sand slides from rest down an icy 90m slope inclined at 30 degrees below the horizontal. The sand leaks from the back of the toboggan at a rate of 2.3kgsec^-1. How long does it take the toboggan to reach the bottom of the slope?

2. Homework Equations
previous equations involved rockets and the equation:

v(final) = v(initial) + u ln(mi/mf)
where u is the exhaust speed

not sure if this relates to this question though?



3. The Attempt at a Solution

I drew the situation but can't see how to find the time, any suggestions please?

 

[Meir Achuz]

The rocket equation doesn't apply here. The exhaust speed is zero.
Apply Fdt=P-P' to your situation.