Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is...
-
Upload
asher-matthews -
Category
Documents
-
view
220 -
download
0
Transcript of Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is...
![Page 1: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/1.jpg)
Unit 2 Notes
![Page 2: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/2.jpg)
Free Body Diagrams
• Show an object and the forces acting on it
• The object is represented by a circle (you can write the object’s name inside the circle)
• Clearly labeled arrows pointing away from the object represent forces acting on the object – Their length represents the magnitude of the force
![Page 3: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/3.jpg)
Good Example
![Page 4: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/4.jpg)
Common Forces
• General push or pull• Gravity• Normal Force– 90 degrees from a surface
• Friction– Resists motion (always in the opposite direction from
motion)
For most forces, whatever exerts the force is listed first followed by the receiver of the force.
![Page 5: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/5.jpg)
Components of Forces
When you are given a force and an angle, make a right triangle with the angle inside the triangle
![Page 6: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/6.jpg)
SOHCAHTOA
is the measure of the angle
𝒔𝒊𝒏𝜽=𝒐𝒑𝒑𝒐𝒔𝒊𝒕𝒆
𝒉𝒚𝒑𝒐𝒕𝒆𝒏𝒖𝒔𝒆
𝒄𝒐𝒔 𝜽=𝒂𝒅𝒋𝒂𝒄𝒆𝒏𝒕
𝒉𝒚𝒑𝒐𝒕𝒆𝒏𝒖𝒔𝒆
𝒕𝒂𝒏𝜽=𝒐𝒑𝒑𝒐𝒔𝒊𝒕𝒆𝒂𝒅𝒋𝒂𝒄𝒆𝒏𝒕
![Page 7: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/7.jpg)
Fopp = Fsin(ϴ)
Fadj = Fcos(ϴ)
![Page 8: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/8.jpg)
Find the x- and y- components of the force
![Page 9: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/9.jpg)
![Page 10: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/10.jpg)
![Page 11: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/11.jpg)
![Page 12: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/12.jpg)
Example 2
![Page 13: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/13.jpg)
![Page 14: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/14.jpg)
![Page 15: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/15.jpg)
Equations of Forces
∑Fy = Upward Forces – Downward Forces
∑Fx = Forces to Right – Forces to Left
(∑ means the summation)
For this unit,∑Fx = 0
∑Fy = 0
![Page 16: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/16.jpg)
Equations of Forces
• When there is no acceleration, the sum of forces in the x-direction is 0 and the sum of forces in the y-direction is 0.
(∑ means the summation)
∑Fy = 0
∑Fx = 0
![Page 17: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/17.jpg)
ExampleA person pushes a 10kg object to the left with a 20N force. Solve for all forces acting on the object.
Step1: Draw a free body diagram.
![Page 18: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/18.jpg)
Step 2: Write the force summation equations.
∑Fx=0 ∑Fy=0
Step 3: Insert Forces into theequations. From here it is a 3-step solution.
Ff -FP/O=0 FN - Fg =0
![Page 19: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/19.jpg)
Fg = 9.8N/kg * 10kg = 98N
Ff -FP/O=0 FN - Fg =0
Ff -20N=0 FN – 98N =0
Ff = 20N FN = 98N
![Page 20: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/20.jpg)
• A person pulls on a 50kgdog’s leash. The dogdoesn’t move.
• Solve for all forces
![Page 21: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/21.jpg)
![Page 22: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/22.jpg)
Ff = 38.6N
∑Fx = 0
FLeash/Dog,x -Ff = 0
∑Fy = 0
38.6N -Ff = 0
FN + FLeash/Dog,y - Fg = 0
FN + 10.4N – 490N = 0
FN – 479.6N = 0
FN = 479.6N
![Page 23: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/23.jpg)
Ramps
• Sometimes it is easier to redefine the x- and y-axes so that they are perpendicular and parallel to a surface
![Page 24: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/24.jpg)
A 5kg block is at rest onan incline as shown.
Solve for the normal force and the force of friction.
![Page 25: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/25.jpg)
Fg = 5kg * 9.8N/kg = 49N
Fg,x = 49N * sin(30) = 24.5N
Fg,y = 49N * cos(30) = 42.4N
![Page 26: Unit 2 Notes. Free Body Diagrams Show an object and the forces acting on it The object is represented by a circle (you can write the object’s name inside.](https://reader036.fdocuments.net/reader036/viewer/2022062322/5697bf771a28abf838c8153f/html5/thumbnails/26.jpg)
-Ff + Fg,x = 0-Ff + 24.5N = 0
Ff = 24.5N
∑Fx = 0 ∑Fy = 0
FN - Fg,y = 0
FN – 42.4N = 0