1. Two-Dimensional Motion
Inclined Planes

2. A simple block on an incline
Inclined Planes
A simple block on an incline
A simple block on an incline
30° Fg

3. Inclined Planes B/c the block in on an incline,
we adjust our coordinate system to fit the incline Y
A simple block on an incline X
30° Fg
Aligning the X axis with the Incline

4. Inclined Planes
Notice the gravitational force (Fg) is pulling straight down
Doesn’ t the Fg also pull you down the hill?
YEP!
So, there are components of the Fg
(x and y)

5. Inclined Planes
There is an Fgx and an Fgy
Fgx
Fgy Fg

6. Inclined Planes
Notice that the coordinate system has been adjusted… How much? Y X
30° Fg
It has been adjusted by the incline, 30°

7. Inclined Planes Therefore the angle between Fg and Fgy is… 30° Fgx Fgy

8. Inclined Planes Therefore the angle between Fg and Fgy is… 30° Fgx Fgy

9. Inclined Planes Now we are able to solve for fgx and fgy
Fgx is the force pulling the block down the incline
Fgy is the force keeping the block in contact with the incline

10. Inclined Planes
Realign the vectors (Tip-to-Tail) to complete a right triangle and you get…
Fgy
30° Fg
30°
Fgx

11. Inclined Planes
Lets take a closer (magnified) look at the similar triangle
Fgy
30° Fg
30°
Fgx

12. Inclined Planes
Lets take a closer (magnified) look at the similar triangle Y
Nice!
Fgy
30°
Fgx X Fg

13. Inclined Plane Problem
A 784-N skier on a hill that makes a 35 angle with the horizontal begins to accelerate down the hill.
Draw the pictorial diagram and free-body diagram
What is the component of the skier’s weight parallel to the incline plane?
What is the normal force?