Kinetic Energy (Monday's Class)

On Monday, we started off reviewing four questions:

(1) Power = (Work)/(Time)

(2)Total Mechanical Energy of an object = KE (Kinetic Energy) + PE (Potential Energy)

(or more simply - mechanical energy is the ability to do work)

(3) The unit for work is the Joule (J).

(4) As a mass increases in velocity, the kinetic energy increases, as well.

THEN we learned about our quiz...YIKES!  It looks like as a whole, the classes combined did not understand the information, so here are some ideas of what went wrong, and how we can fix it for next time!

What went wrong:

• Units were a big problem.  People either forget them, got them wrong, or they were inconsistent throughout the problem.  Just make sure you have the correct units in the final answer.
• Simple 5th grade math errors occurred - check your work!
• Make sure your read the question correctly and underline what it is Mr. Wirth is asking for...and finally...
• Use the correct equations - that's what the reference tables are for!

How we can fix it!:

• Do your homework and ask questions - remember, the midterm is only in 16 days!
• Go in for some extra help with Mr. Wirth
• Or just ask a friend on a topic that you don't understand

24 people getting an F on the test?  Come on, people, we can do better than that!

Onto Kinetic Energy:

Kinetic Energy is associated with MOTION of an object.

An object that has motion (whether horizontal or vertical) has kinetic energy.

The equation: KE = (1/2)mv^2

and...

KE = Kinetic Energy

m = mass of the object in kilograms

v = velocity in meters per second

Remember: Kinetic energy is a scalar quantity, meaning that it does not have a direction.  It is described by magnitude alone.  Like work, the standard unit for kinetic energy is the Joule (J).

Here is an example for an equation on how to solve for kinetic energy:

Determine the kinetic energy of a 625-kg roller coaster that is moving with a speed of 18.3 m/s.

E: KE = (1/2)mv^2

S: KE = (1/2)(625 kg)(18.3m/s)

A: 1.05 x 10^5 Joules