What will be the speed of the mass after sliding 4.0 m along the plane?

Question

A 2.0-kg mass is released from rest at the top of a plane inclined at 20 degrees above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

Answer 1

The net force on the mass is...

F down - F friction = mgsin(20) - .20*m*g*cos(20) = ma

a= 1.51 m/s^2

This is a "Big 4" problem...

d=4.0 m; a=1.5 m/sec^2 (2 sig figs); vo=0 m/s

vf = 3.5 m/sec i9n 2.3 sec

using vf^2 = vo^2 + 2ad and vf=vo+at as equations of motion.

You may also do this problem using energy considerations.  Most students find the bookkeeping a bit more difficult, though.

-Fred