1. 2016/9/12 Relative motion Projectile motion Newton's laws of motion
Physics 111 SI
2016/9/12
Relative motion
Projectile motion
Newton's laws of motion

2. Questions?

3. Sessions setup Mondays: Review and preview with PowerPoint outline
Tuesdays: Worksheets and open for in-session questions
Wednesdays: Worksheets and open for in-session questions
Answer keys of ppts and worksheets won’t be uploaded on SI website

4. Relative motion
Velocity of the moving objects with respect to other moving or stationary object is called “relative velocity” and the motion is called “relative motion”.

5. Relative motion
Let’s say a person is walking on a train at 2 m/s in the opposite direction of the train’s motion at 8 m/s. How fast this person is going relative to someone on the ground?
VPT + VTG = VPG
-2 m/s + 8 m/s = 6 m/s

6. Relative motion

7. Projectile motion
We will consider projectiles in free fall where we neglect air resistance and curvature of the Earth (which most questions you will meet in PHYS 111 do).
With the most common choice of coordinate system:

8. Projectile motion

9. Newton's laws of motion

10. Newton's laws of motion
Fill in blank with [constant], [mass], [magnitude] and [rest]:
1st: An object will remain at [?] or in motion with [?] velocity unless acted by a net external force.
2nd: An object accelerates if a net external force acts on it. The acceleration equals to the force divided by the object’s [?].
3rd: Whenever one body exerts a force on a second body, the second body exerts an oppositely directed force of equal [?] on the first body.

11. Newton's laws of motion
Fill in blank with [constant], [mass], [magnitude] and [rest]:
1st: An object will remain at [rest] or in motion with [constant] velocity unless acted by a net external force.
2nd: An object accelerates if a net external force acts on it. The acceleration equals to the force divided by the object’s [mass].
3rd: Whenever one body exerts a force on a second body, the second body exerts an oppositely directed force of equal [magnitude] on the first body.

12. Newton's laws of motion What is the acceleration of the boxes?
What is the magnitude of equal forces between the two blocks?