Work happens when transforming energy into another form.
Gravity does work to convert potential energy to kinetic while a ball falls. When you lift a ball up, you are do work transforming and storing potential energy back in the ball.
The MKS units for different forms of energy including transforming one to another, or work, is the Joule (J). In this unit, we will talk about mechanical energy that consists of potential and kinetic energy.
Work and Power Variables and Units
Work Equation Facts
Only the force component in the direction of motion does work. When pulling a suitcase, using a handle at an angle, you will only get a portion creating work. So only get the component in the direction or parallel to the motion goes into work.
The following questions seen in the image are using the basic work equation.
No Motion Means No Work
When applying force to an object that does not move, there is no work done. No matter how hard you push a wall, if it does not move, you do no work.
If you climbing upwards you would carry your weight up a distance or height. Just a reminder that weight (Fw = mg) and g is the acceleration due to gravity (g = g = 9.8 m/s2).
1. How much work is a stickman doing while pushing a box 5 meters with a force of 12 N forward?
2. What is the power output of the stickman that pushes the box 5 meters in 3 seconds with a constant force of 12 N?
Work and Power When Force is at an Angle
When force is at an angle, you only get the component in the direction of motion applied to work. The way the picture here is drawn the red arrow would be the component. Since we are trying to determine the adjacent side, we use the cosine function, which has adjacent, and hypotenuse included.
3. How much work do you have when 12 N of force were applied on an object at an angle of 25° above the horizon to move an object 5 meters horizontally?
4. What is your power output when applying 12 N of force on an object at an angle of 25° above the horizon to move it 5 meters horizontally in 3 seconds?
Work and Power Practice Quiz
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