Physics-dynamics question with incline?

  • #1
No matter how many times i do it, i seem to be doing something wrong :|

Homework Statement


A wet bar of soap (150 g) slides without friction down a ramp (2.0 m) long inclined at 7.3degrees. How long does it take to reach the bottom? Neglect friction.
& How would this change if the soaps mass were 250 grams?

Homework Equations



stated below>>

The Attempt at a Solution


So i tried to calculate Fnet using sine.
since Fg=1.5kg*9.8=14.7N
Then i did, sin7.3=x(aka fnet) / 14.7
x = 12.5

Then: Fnet = ma
12.5=0.15a
a=83.3

then
d=vit+1/2at^2
2=0+1/2(83.3)t^2
2/(1/2*83.3)=t^2
Suqareroot(0.048)=t
t=0.219 or around there.

However the answer is 1.8 seconds?
Can anyone help me see what im going wrong?

Any help is much appreciated, thanks.


EDIT:::
Sorry, nevermind, turns out my calc was in radian mode -facepalm- Good grief.
 
Last edited:

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