How to find acceleration of object without mass?

[grbd920]

1. A ship is launched into the water down a ramp making an angle of 8 degrees with the horizontal. The coefficient of kinetic friction between the bottom of the ship and the ramp is μk=0.06. What is the acceleration of the ship down the ramp?2. I know that the equation to solve this is
a = gsin(theta) - μkgcos(theta)
Which gives you 0.8 m/s^23. So, I have the equation to solve it and the correct answer but I'm just not sure how to derive that equation in the first place?

 

[gneill]

Hi grbd920, Welcome to Physics Forums!

Please retain the formatting template headers when you create your homework help requests.

Draw the FBD for the problem and assign a variable, say M, to the mass. Write the equations. You should find that the M cancels out along the way to the solution.

 

[grbd920]

Hi grbd920, Welcome to Physics Forums!

Please retain the formatting template headers when you create your homework help requests.

Draw the FBD for the problem and assign a variable, say M, to the mass. Write the equations. You should find that the M cancels out along the way to the solution.

Got it! Thank you! :)