Lect05 FBD, ropes,springs

# Lect05 FBD, ropes,springs - Physics 211: Lecture 5 Todays...

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

Physics 211: Lecture 5, Pg 1 Physics 211: Lecture 5 Physics 211: Lecture 5 Today’s Agenda Today’s Agenda More discussion of dynamics Recap Newton's Laws The Free Body Diagram Free Body Diagram tension ) Hooke’s Law ( springs ) Original: Mats A.Selen Modified: W.Geist

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

View Full Document
Physics 211: Lecture 5, Pg 2 Review: Newton's Laws Review: Newton's Laws Law 1 : An object subject to no external forces is at rest or moves with a constant velocity if viewed from an inertial reference frame. Law 2 : For any object, F NET = m a Where F NET = Σ F Law 3 : Forces occur in action-reaction action-reaction pairs, F A ,B = - F B ,A . Where F A ,B is the force acting on object A due to its interaction with object B and vice-versa. m is “mass” of object
Physics 211: Lecture 5, Pg 3 Gravity: Gravity: Mass vs Weight Mass vs Weight What is the force of gravity exerted by the earth on a typical physics student? Typical student mass m = 55kg g = 9.81 m/s 2 . F g = mg = (55 kg)x(9.81 m/s 2 ) F g = 540 N = WEIGHT F E,S = - = - m g g F S,E = F = F g = = m g g

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

View Full Document
Physics 211: Lecture 5, Pg 4 Lecture 5, Lecture 5, Act 1 Act 1 Mass vs. Weight Mass vs. Weight An astronaut on Earth kicks a bowling ball straight ahead and hurts his foot. A year later, the same astronaut kicks a bowling ball on the moon in the same manner with the same force. His foot hurts. .. (a) more (b) less (c) the same
Physics 211: Lecture 5, Pg 5 Lecture 5, Lecture 5, Act 1 Act 1 Solution Solution The masses of both the bowling ball and the astronaut remain the same, so his foot will feel the same resistance and hurt the same as before. Ouch.

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

View Full Document
Physics 211: Lecture 5, Pg 6 Lecture 5, Lecture 5, Act 1 Act 1 Solution Solution However the weights of the bowling ball and the astronaut are less: Thus it would be easier for the astronaut to pick up the bowling ball on the Moon than on the Earth. W = m g Moon g Moon < g Earth
Physics 211: Lecture 5, Pg 7 The Free Body Diagram The Free Body Diagram Newton’s 2nd Law says that for an object F = m a . Key phrase here is for an object for an object . Object has mass and experiences forces Object has mass and experiences forces So before we can apply F = m a to any given object we isolate the forces acting on this object:

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

View Full Document
Physics 211: Lecture 5, Pg 8 The Free Body Diagram. .. The Free Body Diagram.
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 12/05/2009 for the course PHYSICS PHYS taught by Professor Phys during the Spring '09 term at Abu Dhabi University.

### Page1 / 36

Lect05 FBD, ropes,springs - Physics 211: Lecture 5 Todays...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online