Astronuc said:Why sin or cos of 348, which looks like 360°-12°?
Work, like energy, is a scalar.
Work is given by the force applied over a distance.
One must assure the force is correctly characterized. Find the component of the gravitational force (weight) acting parallel with the incline. The friction is proportional (via friction factor) to the gravitational force component acting normal to the incline.
http://hyperphysics.phy-astr.gsu.edu/hbase/N2st.html
Friction is a force that opposes motion, while gravity is a force that pulls objects towards the center of the earth. When working on an incline, friction acts in the opposite direction of motion, while gravity pulls objects downwards.
Friction can slow down an object's motion on an incline, as it acts in the opposite direction of the object's movement. This can make it more difficult to move an object up an incline.
The steeper the incline, the greater the amount of friction present. This is because as the angle of the incline increases, the component of gravity pulling the object downwards also increases, resulting in more friction.
The weight of an object is directly related to the force of gravity acting on it. The greater the weight of an object, the greater the force of gravity pulling it downwards. This can make it more difficult to move an object up an incline.
Some examples include pushing a heavy box up a ramp, sliding down a playground slide, and walking up a steep hill. In all of these situations, friction and gravity are both at play, affecting the motion of objects on an incline.