IN WHAT FORMS, OR TYPES, DOES ENERGY APPEAR?

• Potential energy is often referred to as stored energy. It can come in many forms:– Energy in food and gasoline– Gravitational, such as a tree about to

fall– nuclear-----energy in the nucleus of an

atom that is released by fusion or fision

– Mechanical, such as energy that is stored in a spring or rubber band

• Kinetic energy is the energy an object possesses because of its motion:– Heat – Light– Sound– Thermal– Electrical– Radiant

• The ability to cause objects to change, move, or do work

• In this activity, you will explore gravitational potential energy and kinetic energy

WHAT IS ENERGY (DEFINITION)?

How can you transfer How can you transfer energy to the nail so that it energy to the nail so that it drives into the foam block?drives into the foam block?

• The change from one type of energy, such as potential to kinetic

ENERGY TRANSFORMATION

ENERGY TRANSFERENERGY TRANSFER

• The transfer of energy from one object to another

Title: Drive a Nail

Read pg. D-8

Problem: How does the height and mass of an object affect its gravitational potential energy?

Hypothesis/Initial Thoughts:

Activity 54

• It is a variable that can be controlled• What is the manipulated (or independent)

variable or variables?• What is the measured (or dependent)

variable or variables?• What are the energy transformations and

transfers involved?• Can I push the rod down each time? Why

or why not?

WHY IS IT IMPORTANT TO HOLD THE ROD IN THE SAME PLACE EVERY TIME?

WHAT DO WE KNOW ABOUT:•variable?

– Drop height– Mass of object being dropped– Initial depth of the nail in the foam– Angle of drop– Starting position of drop– Dropping rather pushing the rod– Number of drops to push the nail all way into the foam

•reproducibility?•control?

– You must control all variables except the one you are testing– What other variables are controlled?

WITH YOUR GROUP DO PROCEDURE STEPS 1-6. WRITE YOUR PROCEDURE ON NOTEBOOK PAPER.

Questions to think about:•What is the purpose?•What variable are you testing?•What variable will you keep the same?•What is your control?•Will you collect quantitative or qualitative data or both?

Sample procedure:1.Stick the nail ________into the foam block so the nail head is _____ above the foam.2.Put the plastic tube _____________________________.3.Hold the long steel rod over the top of the tube so that its bottom is _____________________________________.4.Drop, don’t push the rod down the tube.5.Repeat steps 1-4 until ____________________________.6.Feel the nail and surrounding area for warmth.7.Record in a data table the number of times the rod was dropped.8.Gently remove the nail.9.Repeat steps 1-8 using the short steel rod.10.Repeat steps 1-8 using the long aluminum rod.11.Repeat steps 1-8 using the short aluminum rod.12.Repeat the experiment using the short plastic tube

Tube

Rod (number of drops)

Long steel Short steelLong aluminum

Short aluminum

Long

Short

Table 1: Drive a Nail Data

WHAT IS THE EFFECT OF CHANGING TWO VARIABLES?

• Both variables cause the nail to be driven deeper into the foam

• The combination of increased initial height and more mass results in more energy transfer

• With everything else being equal, an object with more mass has greater potential energy, likewise an object with greater height has more potential energy

• The greater initial potential energy determines how much kinetic energy the rod has before hitting the nail

• Define gravitational potential energy in the context of the activity• Where did the rod have:

• the most potential energy?• the least amount of potential energy?

• Define kinetic energy in the context of the activity• Where did the rod have:

• the most kinetic energy?• the least amount of kinetic energy?

DISCUSS POTENTIAL VS KINETIC ENERGY

• The nail with the most potential energy before being dropped was transformed into the most kinetic energy

• Give an example of a real-world situation where gravitational potential energy is transformed to do work.

• What is the difference between gravitational potential energy and potential energy?

DISCUSS POTENTIAL VS KINETIC ENERGY