Download presentation

Presentation is loading. Please wait.

1
**Chapter IV Work and Energy**

Work Done by a Constant Force The Work-Energy Theorem Work Done by a Varying Force or on Curved Path Power Gravitational Potential Energy and Elastic Potential Energy When Total Mechanical Energy is Conserved

2
**A. Work Done by a Constant Force**

Fx = F cos x The work W done on an object by an agent exerting a constant force on the object is the product of the component of the force in the direction of the displacement and the magnitude of the displacement: W = F X W = F Cos X F W x

3
**B. The Work-Energy Theorem**

W = F x = m a x v 2 = vo2 + 2 a x Kinetic energy K = ½ m v2 W = K – Ko Wt = K work-kinetic energy theorem The net work done on a particle by a constant net force F acting on it equals the change in kinetic energy of the particle

4
**C. Work Done by a Varying Force or on Curved Path**

W = F x W = W = Limit F x x 0 W = F dx = m a dx a = dv/dt = (dv/dx)(dx/dt) = (dv/dx) v W = m a dx = m (dv/dx) v dx W = m dv v W = ½ m v 2 - ½ m vo2 = K – Ko Wt = K W W x x The net work done on a particle by the net force acting on it is equal to the change in the kinetic energy of the particle. By spring F = - k x By hand F = k x W = F dx = k x dx = ½ k x2 Elastic Potential Energy

5
**D. Power P = Power (watt W) W = work (joule J)**

The time rate of doing work is called power. P = Power (watt W) W = work (joule J) t = time (second s) x = displacement (meter m) v = velocity (m/s)

6
**E. Gravitational Potential Energy and Elastic Potential Energy**

W = F y = mg (h2 – h1) = m g h2 - m g h1 Gravitational potential energy = V = mgh W = V2 – V1 W = V work done by palm force W = - V work done by gravitation force WK = - V h2 v h1 WK = work done by concervative force (J) g = acceleration of gravity (m/s2) m = mass(kg) V = Potential energy (J) WK = - (½ k x22 - ½ k x12 ) work done by spring force k = force constant of the spring(J/m2 N/m)

7
Conservative Force Conservative forces have two important properties: 1. A force is conservative if the work it does on a particle moving between any two points is independent of the path taken by the particle. 2. The work done by a conservative force on a particle moving through any closed path is zero. (A closed path is one in which the beginning and end points are identical.)

8
**E. When Total Mechanical Energy is Conserved**

Wt = WNK + WK WNK = Wt – WK WNK = K – (- V) WNK = (K2 – K1) + (V2 – V1) WNK = work done by nonconcervative force (J) If WNK = 0, than K1 + V1 = K2 + V2 Mechanical energy M = K + V M1 = M2 M = constant ½ m v 2 + mgh = constant Conservation of Mechanical Energy

9
Increase (or decrease) in potential energy is accompanied by an equal decrease (or increase) in kinetic energy. The total mechanical energy of a system remains constant in any isolated system of objects that interact only through conservative forces.

Similar presentations

OK

Work and Energy. Work Done by a Constant Force Work: The __________done by a constant ________acting on an object is equal to the product of the magnitudes.

Work and Energy. Work Done by a Constant Force Work: The __________done by a constant ________acting on an object is equal to the product of the magnitudes.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on monetary economics Ppt on 60 years of indian parliament session Ppt on pi in maths lesson Ppt on mobile and wireless networks Maths ppt on exponents and powers Ppt on uses of concave and convex mirror Ppt on jawaharlal nehru in hindi language Ppt on shielded metal arc welding Ppt on production management information system Ppt on instrument landing system