Posted by simon on Monday, September 24, 2012 at 6:04am.
A boy is sledding down a slope that is inclined at 30.0° with respect to the horizontal. A moderate wind is aiding the motion by providing a steady force of 108 N that is parallel to the motion of the sled. The combined mass of the boy and sled is 53.6 kg, and the coefficient of friction between the runners of the sled and the snow is 0.150.
What is the acceleration of the boy and his sled?

physics  Elena, Monday, September 24, 2012 at 3:28pm
x: m•a= m•g•sinα +F  F(fr),
y: 0=  m•g•cosα +N.
F(fr)=μ•N= μ• m•g•cosα
m•a= m•g•sinα +F  μ• m•g•cosα
a= g(sinα  μ•cosα)+ F