PHY101_Chap5Fall09

PHY101_Chap5Fall09 - Chapter 5 ENERGY 5.1 Work Work = F. x...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 5 ENERGY
Background image of page 1

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

View Full DocumentRight Arrow Icon
5.1 Work Work = F. Δ x
Background image of page 2
5.1 Work • The work, W , done by a constant force on an object is defined as the product of the component of the force along the direction of displacement and the magnitude of the displacement • This gives no information about – the time it took for the displacement to occur – the velocity or acceleration of the object • Work is a scalar quantity
Background image of page 3

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

View Full DocumentRight Arrow Icon
A worker pushes a sled with a force of 40 N over a level distance of 6.0 m. If a frictional force of 24 N acts on the wheelbarrow in a direction opposite to that of the worker, what net work is done on the wheelbarrow? 1. 240 J 2. 216 J 3. 144 J 4. 96 J Quiz Qn. 3
Background image of page 4
Work – F is the magnitude of the force Δ x is the magnitude of the object’s displacement θ is the angle between
Background image of page 5

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

View Full DocumentRight Arrow Icon
Work done example The total mass of fish and sled = 50 kg. F = 120 N and he pulls it for 5 m. How much work is done if θ = 0 How much work is done if θ = 30 o
Background image of page 6
When Work is Zero • Displacement is horizontal • Force is vertical • cos 90° = 0
Background image of page 7

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

View Full DocumentRight Arrow Icon
Work Can Be Positive or Negative • Work is positive when lifting the box • Work would be negative if lowering the box – The force would still be upward, but the displacement would be downward
Background image of page 8
Work – F is the magnitude of the force Δ x is the magnitude of the object’s displacement θ is the angle between
Background image of page 9

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

View Full DocumentRight Arrow Icon
5.2 Kinetic Energy • Energy associated with the motion of an object • Scalar quantity with the same units as work • Work is related to kinetic energy
Background image of page 10
5.2 The Work-Energy Theorem and Kinetic Energy • Energy: when work is done, energy changes • Many forms of energy: chemical energy, nuclear energy, electric/magnetic energy, mechanical energy … – Total energy is conserved • Energy can do things
Background image of page 11

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

View Full DocumentRight Arrow Icon
• An object’s kinetic energy can also be thought of as the amount of work the moving object could do in coming to rest – The moving hammer has kinetic energy and can do work on the nail
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/02/2010 for the course PHY 101 taught by Professor Pralle during the Fall '08 term at SUNY Buffalo.

Page1 / 42

PHY101_Chap5Fall09 - Chapter 5 ENERGY 5.1 Work Work = F. x...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online