Free Body Diagram

1. Free Body Diagram

2. m q Force Vectors • Force is a vector. • A block sliding on an inclined plane has forces acting on it. • We know there is a force of gravity and normal force.

3. m q Force Diagram • Draw the forces acting on the block. • The force of gravity points down with magnitude Fg=mg. • The normal force points away from the surface of the inclined plane.

4. m q Force Diagram • Draw components of the forces so the vectors can be added. • The coordinates should point along the surface. • The normal force is unknown • The motion will be along the surface • The components of Fg are compared to the surface.

5. m q Net Force • The block stays along the plane. • No motion or acceleration away from the surface • No force in that component • Solve for the normal force: • Net force:

6. m q Motion from Force • The net force causes the block to accelerate. • The amount of acceleration is force divided by mass. • This is a constant acceleration moving the block.

7. m q Inclined Plane • Pushing a block up an incline is easier than lifting. • To get constant velocity a force equal to the downward acceleration must be applied.

8. m q Mechanical Advantage • The inclined plane has been used as a machine for centuries. • Pushing a block up an incline is easier than lifting. • The ratio of the force to lift directly compared to the force using the incline is the mechanical advantage. next