Days To Remember G's Blog

Physics Day

Station 1

Discuss gravity, what gravity is and what it does.  Gravity: the force that attracts a body toward the center of the earth, or toward any other physical body having mass.

What is the difference between mass and weight? 

Mass:  A measure of how much matter an object has

Weight:  a body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing.  Weight has to do with the gravitational pull on the object.   That is why if we were to visit different planets we would weigh differently, it is due to gravity. 

Experiment with gravity: (All things fall down due to earth’s gravity)

Question:  Why do heavy and light objects fall at the same speed?  Use rock and feather

Answer:  How fast something falls due to gravity is determined by a number known as the "acceleration of gravity", which is 9.81 m/s^2 at the surface of our Earth. Basically this means that in one second, any object's downward velocity will increase by 9.81 m/s because of gravity. This is just the way gravity works - it accelerates everything at exactly the same rate.

What you may be getting confused by is the fact that the force of gravity is stronger on heavier objects than lighter ones. Another way of thinking of this is to say that gravity has to pull harder on a heavy object than a light one in order to speed them both up by the same amount.

However, in the real world, we have things like air resistance, which is why sometimes heavy things do fall faster. For example, if you drop a feather and you drop a rock, the rock will land first since the feather is slowed down more by the air. If you did the same thing somewhere where there is no air, the feather and the rock would land at exactly the same time.

Now moving on to the egg drop we need to look at force = mass X acceleration. 

Acceleration:  the increase of speed or velocity

Force:  is a push or pull upon an object resulting from the object's interaction with another object.

Finding Force and differences in Weight

If your mass is 50 kg on earth what is your mass on the moon? 

If your weight is 50 kg on earth what is your weight on the moon if the moon’s gravitational pull is 1/6 of that on the earth?

F = m x g     (Newtons)

Force = mass (kg) x gravitational pull  (m/s2)

On the earth 50 kg x 9.8 m/s2 =

On the moon 50 kg x 1.6 m/s2 =

Weigh yourself and convert your pounds to kg. 

1 pound = 0.45 kg

So,   80 pounds (lb)   x            __0.45 kg__  = 36.29 kg

                                                                                    1 lb

Now using the equation above find your weight on the moon. 

Station 2

Talk about Energy

First law of Thermodynamics: No new matter is being created nor destroyed, it only changes form

Second law of Thermodynamics:  everything is going toward a state of disorder  (like if you leave your bike outside in the rain it starts to rust and decay)

What is the difference between potential and kinetic energy? 

(Show a America’s Funniest videos of people on bikes) 

Potential energy is energy that is stored due to the objects position.  Like a boulder on top of a hill.

Kinetic energy is energy in motion.  The boulder rolling down the  hill.

(Have students design roller coasters, water flumes, or bobsled flume, and label on the roller coaster, etc., where potential energy and kinetic energy are located during the ride).  Need large sheets of paper and pencils, crayons, maybe markers. 

Station 3

Talk about how energy changes form from electrical, to sound, thermal, light, heat. 

Maybe have them come up with ways energy changes form in a comic strip or pictures and tell each other how their energy changed form. 

Ex)  Plant absorbs energy from the sun, changes it to sugar, then plant decays, now it is oil or coal, then coal or oil is burned, emits heat and gives off light

Then you can give students time to either form teams or individually start creating a contraption for their egg next week.  You will need to gather materials for their contraptions. 

THE EGG DROP

The egg drop experiment for physics involves placing an egg in a container with a number of materials around it as protection and then having to drop the egg from a given height so that it won't break. You need to figure out which container and materials would best protect the egg from breaking upon impact. You also need to consider the techniques you could use to improve your chances of a successful outcome.

Guidelines:

1)      You may use any materials you wish to build your egg case contraption.

2)      The container may not exceed 1000 grams or 35 ounces, the container that is the lightest that still has the egg in tact is the winner. 

The eggs will be dropped from an initial height of at least 15 meters.  The object is to have your egg drop without breaking.

We will be giving you eggs the day of the activity, please make sure you bring necessary tools (tape, etc.) to close up your case and then have it weighed by one of the judges. 

***Here is an example of an egg drop contest.

EGG DROP COMPETITION GUIDELINES

GENERAL:

The contestants shall design and build a shipping container that will prevent an uncooked

chicken egg (Grade A Large) from breaking when dropped from an initial height of 15 meters.

At the discretion of the judges, surviving eggs with then be taken higher and dropped a second

time. The maximum weight, including the egg, can not exceed 1, 000 grams or 35 ounces. Contestants must be able to remove the egg without damage

MATERIALS:

Any material may be used in the design, as long as the structure meets the design and contest

rules as outlined below.

DESIGN AND CONTEST RULES:

1.No kits or pre-made designs may be used. The structure must be the individual’s invention.

2.The structure must land in a designated target area

3.No propulsion systems will be allowed.

4.No gases (i.e. helium) other than air can be present in the structure when it is weighed.

JUDGING:

1.Grade A Large eggs will be supplied at the competition. You can not bring your own egg.

2.All containers will be inspected by judges before they are dropped.

3.Once an egg is weighed-in with the structure, that egg cannot be exchanged with another.

4.The egg must be placed into the container on-site.

5.The egg must be undamaged after the drop in order for the contestant to be recorded, the lightest weight without breaking will win.