KINETIC ENERGY
Objects have energy because of their motion; this energy is called kinetic energy. Kinetic energy of the objects having mass m and velocity v can be calculated with the formula given below; K=1/2mv²

Kinetic energy is a scalar quantity; it does not have a direction. Unlike velocity, acceleration, force, and momentum, the kinetic energy of an object is completely described by magnitude alone. Like work and potential energy, the standard metric unit of measurement for kinetic energy is the Joule. As might be implied by the above equation, 1 Joule is equivalent to 1 kg(m/s) 2.

Examples
1. Determine the kinetic energy of a 625-kg roller coaster car that is moving with a speed of 18.3 m/s. Answer:
KE = 0.5mv2
KE = (0.5)(625 kg)(18.3 m/s)2
KE = 1.05 x105 Joules
2. If the roller coaster car in the above problem were moving with twice the speed, then what would be its new kinetic energy? Answer:
KE = 0.5mv2
KE = 0.5(625 kg)(36.6 m/s)2
KE = 4.19 x 105 Joules

Work-Energy Theorem

Relationship between KE and W: The word done on an object by a net force equals the change in kinetic energy of the object:

Wnet = Kf - Ki
This relationship is called the work energy theorem
W = Fdcosø
When the energy of the body increases, work is positive.

Examples:

1. A boy pushes a 5.00 kg cart in a circle, starting at 0.500 m/s and accelerating to 3.00 m/s. How much work was done on the cart? Answer:

W= Kf- Ki = (0.5)m(vfinal)2 - (0.5)m(vinitial)2
W = (0.5)(5.00)(3.00)2 - (0.5)(5.00)(0.500)2
W = 21.9 J

2. A 1000.0 kg truck accelerates from 20.0 m/s to 25.0 m/s over a distance of 300.0 m. What is the average net force on the truck?

Answer:

W = Kf- Ki = (0.5)m(vfinal)2 - (0.5)m(vinitial)2
W = (0.5)(1000.0kg)(25.0m/s)2 – (0.5)( 1000.0kg)(20.0m/s)2...

...of mass m initially at speed u collides head-on (without rotation) with a stationary puck of mass M. Find the velocities of both puck after the collision if: i) the collision is fully elastic ii) the collision if fully inelastic. i) momentum: kineticenergy: mu = mv+MV (+ve in direction of initial u) 1 /2 m u2 = 1/2 m v2 + 1/2 M V2
2 eqns in 2 unknowns: V = (u - v) m/M substitute in K eqn: u2 = v2 + (M/m) V2 = v2 + (M/m) (u - v)2 (m/M)2 = v2 + (u - v)2 (m/M) let...

...Experiment 7: Work, Power and Energy
Laboratory Report
John Karl Macrohon
Department of Math and Physics
College of Science, University of Santo Tomas
España, Manila Philippines
Abstract
The experiment is subdivided into two activities: Power and Energy of a Tossed Ball (Physics with Computers). The work done by gravity on each member when going up and downstairs of the second and third floors of the Main Building and the power output of each member of...

...Experiment 4: Work, Power and Energy
Arlie Bamiano, Jealine Marie Bernabe, Petrenne Clarice Caimbon, Jhia Caso
Department of Biological Sciences
College of Science, University of Santo Tomas
España, Manila Philippines
Abstract
The experiment deals primarily with computing the work done by gravity on each member in two scenarios (going up and down the stairs of the second floor and the third floor of the Main Building) wherein weight was also considered and...

...to zero. In other words, there is no net torque on the object.
* Note that the SI units of torque is a Newton-metre, which is also a way of expressing a Joule (the unit for energy). However, torque is not energy. So, to avoid confusion, we will use the units N.m, and not J. The distinction arises because energy is a scalar quanitity, whereas torque is a vector.
Torque
If a net force is applied to an object’s center of mass, it will not...

...conservation of mechanical energy
Section: 8
Name: Ahmed Atari
University ID: 201103848
Instructor: Ahmed Zainelabdin
Submission date: May 1, 2014
Objective: the purpose of this lab is to investigate the law of conservation of energy. This can be achieved by measuring both potential and kineticenergy through the experiment conducted.
Back ground:...

...Part B
Now, suppose that Zak's younger cousin, Greta, sees him sliding and takes off her shoes so that she can slide as well (assume her socks have the same coefficient of kinetic friction as Zak's). Instead of getting a running start, she asks Zak to give her a push. So, Zak pushes her with a force of 125 \rm N over a distance of 1.00 \rm m. If her mass is 20.0 \rm kg, what distance d_2 does she slide after Zak's push ends?
Remember that the frictional force acts on Greta...

...Potential Energy
• Definition and Mathematics of Work
• Calculating the Amount of Work Done by Forces
• Potential Energy
• KineticEnergy
• Mechanical Energy
• Power
An object can store energy as the result of its position. For example, the heavy ball of a demolition machine is storing energy when it is held at an elevated position. This stored energy of position is referred...

...would travel away from the earth into the solar system. |
| | It would take less time to reach its bound orbit. |
| | It would orbit the earth at a faster velocity. |
| | | | |
Question 7 | 1.61 points | Save |
| When energy is converted from one form to another, a tiny amount is inevitably lost. | | | | |
| | True |
| False |
| | | | |
Question 8 | 1.61 points | Save |
| There is no gravity in space. | | | | |...