On this display we have setup the initial conditions for a 1 kg sliding box. Answer these questions. How long does it take the box to reach the origin? What is its speed at x=0? How would these results change if the box had a 2kg mass.

You should have found that it takes about 2.15 seconds to reach the origin with a speed at that point of about 10.58m/s. To check out the effect of doubling the box mass, change mass to 2 on the free body diagram. Then remember to double the magnitude of the forces also because weight is m*g and the plane's reaction force on the box is derived from the weight.