Mechanical Energy

Mechanical Energy

physical science

Mechanical Energy of a System

• the TOTAL ENERGY never changes!!!

• in the picture, total (mechanical) energy is equal to 50,000 Joules

• KE + PE HAS TO EQUAL 50,000 Joules

• look at each point: KE + PE = 50,000 J every time!

Multiple Choice

At some point during a fall, an object has 183 J of KE and 117 J of PE. What is the mechanical energy of the system?

• 300 J
• 66 J
• 21,411 J

Multiple Choice

In the same system as the previous question, the object has 208 J of KE. How much PE does it have?

• 508 J
• 92 J
• 0.69 J

Multiple Choice

At the top of a hill, a car is sitting still and has 2,500 J of PE. What is the mechanical energy of the system?

• 2,500 J
• there is not enough information to answer the qustion
• 0 J

Multiple Choice

In the same system as the previous question, at some point the car is measured to have 575 J of KE. How much PE does the car have at the same point?

• 1,437,500 J
• 1,925 J
• 3,075 J