# Lecture5 - PHYSICS 231 INTRODUCTORY PHYSICS I Lecture 5...

This preview shows pages 1–9. Sign up to view the full content.

PHYSICS 231 INTRODUCTORY PHYSICS I Lecture 5

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Range (y i =y f ): Relative velocity: Newton’s Laws: 1. If Σ F = 0, velocity doesn’t change. 2. 3. Main points of last lecture R = v i 2 g sin2 ! v be = v br + v re r F ! = m r a r F 12 = ! r F 21
Newton’s Third Law Single isolated force cannot exist For every action there is an equal and opposite reaction Action and Reaction Forces act on different objects Force on “1” due to “2” r F 12 = ! r F 21

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Free-body Diagram Draw arrows for all forces acting ON object If the object is in “equilibrium” (at rest or constant v) Otherwise, find acceleration by Ignore rotational motion for now. Treat object as a particle. r F ! = 0 r F ! = m r a
Example 4.1 Two blocks sit on a frictionless table. The masses are M 1 =2 kg and M 2 =3 Kg. A horizontal force F=5 N is applied to Block 1. 1. What is the acceleration of the blocks? 2. What is the force of block 1 on block 2? 1. a = 1 m/s 2 2. F 21 = 3 N M 1 M 2 F

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Mechanical Forces Gravity: w=mg (down) Normal forces Strings, ropes and Pulleys Friction Springs (later)
Rules for Ropes and Pulleys Force from rope points AWAY from object (Rope can only pull) Magnitude of the force is Tension Tension is same everywhere in the rope Tension does not change when going over pulley Approximations: Neglect mass of rope and pulley, neglect friction in pulley

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Example 4.2 I pull a 5 kg mass up with a rope, so that it accelerates 2 m/s 2 . What is the tension in the rope?
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern