Physics repost
posted by Lindsay .
A 2 kg otter starts from rest at the top of a muddy incline 85 cm long ans slides down to the bottom in 0.5 s. What net external force acts on the otter along the incline?
I know which equation I need to use. But how can I use the cm and s to get the acceleration?

NetForce=ma or
a= netforce/m
distance= 1/2 a t^2, use a above, solve for net force. Change cm to m 
I come up with 13.6 N as my net force. Is this correct?

netforce= 2*distance/time=2*.85/time^2=13.6N

Here's what you know, m=2.0 kg, vi=0m/s,Dx=.85 m, Dt=5 s, to find a, use the formula Dx = vi(Dt) + 1/2a(Dt)2,0.85=0(.5)+1/2a(.50)^2, solve for a, a=6.8 m/s^2. Now use the formula F = ma, F=2.0*6.8, solve for F, F=14 N.