SCIENCE NEWS - WHALE EAR WAX #20

WHALE EAR WAX

Cerumen. It’s a lovely word. Especially considering that it means earwax. And we’re not the only species that produces the stuff. Some whales build up waxes, along with lipids and keratin protein into what’s called earplugs. And researchers now know that examining these plugs tells them about a whale’s lifetime exposure to pollution.
Alternating layers of dark and light in the plugs correlate to seasons of feeding or migration. So the plugs have been used to determine a whale’s age. Think tree rings. 
In the latest study, scientists analyzed an earplug from an endangered blue whale killed by a ship near California. They found that levels of stress hormones doubled over the whale’s life.
They also found evidence that the whale had been exposed to pesticides such as DDT, with the highest levels during the whale’s first six months of life. The whale was likely exposed to the pesticides in its mother’s milk.
They also found a couple of peaks of exposure to mercury. The study is in the Proceedings of the National Academy of Sciences. [Stephen J. Trumble et al., Blue whale earplug reveals lifetime contaminant exposure and hormone profiles]
Future earplugs should offer additional clues about whale lives. So look for researchers to give new attention to leviathan cerumen.
—Cynthia Graber

PHYSICS - MOTION

Energy Around Us

We use the concept of energy to help us describe how and why things behave the way they do. We talk about solar energy, nuclear energy, electrical energy, chemical energy, etc. If you apply a force to an object, you may change its energy. That energy must be used to do work, or accelerate, an object. Energy is called a scalar; there is no direction to energy (as opposed to vectors). We also speak of kinetic energy, potential energy, and energy in springs. Energy is not something you can hold or touch. It is just another means of helping us to understand the world around us. Scientists measure energy in units called joules.

Active Energy vs. Stored Energy

Kinetic and potential energies are found in all objects. If an object is moving, it is said to have kinetic energy (KE). Potential energy (PE) is energy that is "stored" because of the position and/or arrangement of the object. The classic example of potential energy is to pick up a brick. When it's on the ground, the brick had a certain amount of energy. When you pick it up, you apply force and lift the object. You did work. That work added energy to the brick. Once the brick is in a higher/new position, we would say that the increased energy was stored in the brick as PE. Now the brick can do something it couldn't do before; it can fall. And in falling, can exert forces and do work on other objects.

Season of Springs

The study of springs is a whole section of physics. A spring that just sits there doesn't do much. When you push on it, you exert a force and change the arrangement of the coils. That change in the arrangment stores energy in the spring. It now contains energy and can expand and do work on other things. Anything that is elastic (can change its arrangement and then restore itself), such as a rubber band, can store energy in the same way.

A rubber band can be stretched and then it is ready to do something. That stretching involves work and increases the potential energy. You can flatten a solid rubber ball and it will want to bounce back up. You can also pull the drawstring of a bow and the work done stores the energy that can make the arrow go flying. Those are all examples of your putting energy in, and then something happening when the energy comes out.

Gases Storing Energy

Gases? What can they do? Gases are great because they can compress and expand. They act as if they were elastic. If the pressure increases and compresses gas molecules, the amount of stored energy increases. It's similar to a spring, but slightly different. Eventually that energy in the compressed gas can be let out to do something (work).

In your car, there are shock absorbers. Some shocks have compressed gas in the cylinders rather than springs. The energy in those cylinders keeps your car from bouncing too much in potholes. Think about wind. Wind is caused because of pressure differences in the atmosphere. When the wind blows it can do anything - turn windmills, help birds fly, make tornadoes, and do all types of work.

 

Motion

Inertia

• Inertia is the tendency of a stationary object to remain at rest, or the tendency of a moving object to continue at the same speed.
• The heavier the object the greater is the inertia.

          Examples of Inertia

1. When a car brakes suddenly, the driver and passengers tend to keep going in the same direction and at the same speed as before braking. Seat belts are therefore needed to stop them going through the windscreen.

2. It is more difficult to push-start a stationary truck than it is to push a small sedan.
3. It is more difficult to stop a moving truck than it is to stop a small sedan.

PHYSICS - FRICTION

Friction Basics

Friction is a force that holds back the movement of a sliding object. That's it. Friction is just that simple.

You will find friction everywhere that objects come into contact with each other. The force acts in the opposite direction to the way an object wants to slide. If a car needs to stop at a stop sign, it slows because of the friction between the brakes and the wheels. If you run down the sidewalk and stop quickly, you can stop because of the friction between your shoes and the cement.

What happens if you run down the sidewalk and you try to stop on a puddle? Friction is still there, but the liquid makes the surfaces smoother and the friction a lot less. Less friction means it is harder to stop. The low friction thing happens to cars when it rains. That's why there are often so many accidents. Even though the friction of the brakes is still there, the brakes may be wet, and the wheels are not in as much contact with the ground. Cars hydroplane when they go too fast on puddles of water.

Friction and Gases

Friction only happens with solid objects, but you do get resistance to motion in both liquids and gases. This doesn't involve sliding surfaces like friction does, but is instead the kind of resistance you get if you try to push your way through a crowd. It's a colliding situation, not a sliding one. If the gas is air, this is referred to as air resistance.

If you were in the space shuttle and re-entering the atmosphere, the bottom of the shuttle would be getting very hot. The collisions that occur between the molecules of the air being compressed by the shuttle, heat up the air AND the shuttle itself. The temperature on the top of the shuttle is also warm, but nowhere near the temperatures found on the bottom.

Friction and Liquids

Although liquids offer resistance to objects moving through them, they also smooth surfaces and reduce friction. Liquids tend to get thinner (less viscous) as they are heated. Yes, that's like the viscosity of the oil you put in your car. Car engines have a lot of moving parts, and they rub on each other. The rubbing produces friction and the result is heat. When oil is added to a car engine, the oil sticks to surfaces, and helps to decrease the amount of friction and wear on the parts of the engine. An engine that runs hotter requires a more viscous oil in order for it to stick to the surfaces properly.

Measuring Friction

Measures of friction are based on the type of materials that are in contact. Concrete on concrete has a very high coefficient of friction. That coefficient is a measure of how easily one object moves in relationship to another. When you have a high coefficient of friction, you have a lot of friction between the materials. Concrete on concrete has a very high coefficient, and Teflon on most things has a very low coefficient. Teflon is used on surfaces where we don't want things to stick; such as pots and pans.

Scientists have discovered that there is even less friction in your joints than in Teflon! It is one more example at how efficient living organisms can be. 

Friction

• Friction is a force opposing the movement of one surface over another.
• The Magnitude of the Force of Friction depends on the following factors:

1. The roughness of the surfaces (e.g. stepping on banana peel compared with carpet)
2. The force pushing the surfaces together (e.g. A heavy truck's tires compared with a bicycle's tires on the road)
3. Whether the surfaces are moving or stopped

• 3 Types of Friction

1. Static Friction - acting between 2 stationary bodies (e.g. holding a person on a chair)
2. Sliding Friction - acting between surfaces where one is moving (e.g. sliding furniture across the floor, writing with a pencil on paper)
3. Rolling Friction - acting between surfaces of objects where one has a rounded shape (e.g. car tyres on the road, ball bearings); less than sliding friction

• 4 Ways to Reduce Friction

1. Reducing the force pushing both surfaces together
2. Using a lubricant such as oil or water between the surfaces
3. Using ball bearings or rollers between both surfaces
4. Polishing both surfaces

SCIENCE NEWS - WHY DOES WATER EXPAND? #19

PHYSICS - FORCES IN LIQUIDS

Forces in Liquids

• Cohesion is the combined effect of the forces of attraction between particles close to each other in the same substance.
• Surface Tension is the cohesion at the surface of liquids. Detergents and liquid temperature affect surface tension.
• Examples of Cohesion and Surface Tension - the rounded shape of a water droplet, clasped pointed hands of divers to reduce surface tension, reduction of surface tension for divers by fountains spraying into the diving pool

• Adhesion is the combined effect of the forces of attraction between the particles in different substances close to each other.
• Capillary Action is the effect that causes liquids to rise or fall in fine tubes. The finer the tube, the higher the liquid will rise up the tube.
• Meniscus - The meniscus is the curved surface of a liquid such as water in a glass or mercury in a thermometer. The curve is caused by the adhesive attraction between the liquid and its container.
• Examples of Adhesion and Capillary Action - Meniscus of water in a glass, the movement of water through the tubes in a tree

PHYSICS - SIMPLE MACHINES QUIZ

Take this quiz - Do Not use your notes.  Record your score and turn into the box today.


SIMPLE MACHINES QUIZ

PHYSICS - VELOCITY, ACCELERATION

Speed it Up, Slow it Down

The physics of motion is all about forces. Forces need to act upon an object to get it moving, or to change its motion. Changes in motion won't just happen on their own. So how is all of this motion measured? Physicists use some basic terms when they look at motion. How fast an object moves, its speed or Velocity, can be influenced by forces. (Note: Even though the terms 'speed' and 'velocity' are often used at the same time, they actually have different meanings.)

Acceleration is a twist on the idea of velocity. Acceleration is a measure of how much the velocity of an object changes in a certain time (usually in one second). Velocities could either increase or decrease over time. Mass is another big idea in motion. Mass is the amount of something there is, and is measured in grams (or kilograms). A car has a greater mass than a baseball.

Simple and Complex Movement

There are two main ideas when you study mechanics. The first idea is that there are simple movements, such as if you're moving in a straight line, or if two objects are moving towards each other in a straight line. The simplest movement would be objects moving at constant velocity. Slightly more complicated studies would look at objects that speed up or slow down, where forces have to be acting.

There are also more complex movements when an object's direction is changing. These would involve curved movements such as circular motion, or the motion of a ball being thrown through the air. For such complex motions to occur, forces must also be acting, but at angles to the movement.

In order to really understand motion, you have to think about forces, acceleration, energy, work, and mass. These are all a part of mechanics.
 

SCIENCE NEWS - ZAMBONI #18

PHYSICS - NEWTON'S LAWS OF MOTION*

Newton's Laws of Motion

There was this fellow in England named Sir Isaac Newton. A little bit stuffy, bad hair, but quite an intelligent guy. He worked on developing calculus and physics at the same time. During his work, he came up with the three basic ideas that are applied to the physics of most motion (NOT modern physics). The ideas have been tested and verified so many times over the years, that scientists now call them Newton's Three Laws of Motion. 

Sir Isaac Newton was one of the greatest scientists and mathematicians that ever lived. He was born in England on December 25, 1643. He was born the same year that Galileo died. He lived for 85 years.Isaac Newton was raised by his grandmother. He attended Free Grammar School and then went on to Trinity College Cambridge. Newton worked his way through college. While at college he became interested in math, physics, and astronomy. Newton received both a bachelors and masters degree.While Newton was in college he was writing his ideas in a journal. 
Newton had new ideas about motion, which he called his three laws of motion. He also had ideas about gravity, the diffraction of light, and forces. Newton's ideas were so good that Queen Anne knighted him in 1705. His accomplishments laid the foundations for modern science and revolutionized the world. Sir Isaac Newton died in 1727.In this lesson you will develop an understanding of each of Newton's Three Laws of Motion.

According to Newton's first law...

An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

This law is often called
"the law of inertia".

First Law
The first law says that an object at rest tends to stay at rest, and an object in motion tends to stay in motion, with the same direction and speed. 

What does this mean?This means that there is a natural tendency of objects to keep on doing what they're doing. All objects resist changes in their state of motion. In the absence of an unbalanced force, an object in motion will maintain this state of motion.

Let's study the "skater" to understand this a little better.


What is the motion in this picture?

What is the unbalanced force in this picture?

What happened to the skater in this picture?  *****************************************************************************This law is the same reason why you should always wear your seatbelt.

Motion (or lack of motion) cannot change without an unbalanced force acting. 

If nothing is happening to you, and nothing does happen, you will never go anywhere. If you're going in a specific direction, unless something happens to you, you will always go in that direction. Forever. 

You can see good examples of this idea when you see video footage of astronauts. Have you ever noticed that their tools float? They can just place them in space and they stay in one place. There is no interfering force to cause this situation to change. The same is true when they throw objects for the camera. Those objects move in a straight line. If they threw something when doing a spacewalk, that object would continue moving in the same direction and with the same speed unless interfered with; for example, if a planet's gravity pulled on it 
(Note: This is a really really simple way of descibing a big idea. You will learn all the real details - and math - when you start taking more advanced classes in physics.). 

According to Newton's second law... Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object). What does this mean?  Everyone unconsiously knows the Second Law. Everyone knows that heavier objects require more force to move the same distance as lighter objects. However, the Second Law gives us an exact relationship between force, mass, and acceleration. It can be expressed as a mathematical equation:  or FORCE = MASS times ACCELERATION Second Law The second law says that the acceleration of an object produced by a net (total) applied force is directly related to the magnitude of the force, the same direction as the force, and inversely related to the mass of the object (inverse is a value that is one over another number... the inverse of 2 is 1/2). This is an example of how Newton's Second Law works: Mike's car, which weighs 1,000 kg, is out of gas. Mike is trying to push the car to a gas station, and he makes the car go 0.05 m/s/s. Using Newton's Second Law, you can compute how much force Mike is applying to the car. Answer = 50 newtons

The second law shows:  

• that if you exert the same force on two objects of different mass, you will get different accelerations (changes in motion). 

The effect (acceleration) on the smaller mass will be greater (more noticeable). 

The effect of a 10 newton force on a baseball would be much greater than that same force acting on a truck. The difference in effect (acceleration) is entirely due to the difference in their masses. 

This is easy, let's go on to
Newton's Third Law of Motion 

According to Newton's third law...

For every action there is an equal and opposite re-action.

What does this mean? 

This means that for every force there is a reaction force that is equal in size, but opposite in direction. That is to say that whenever an object pushes another object it gets pushed back in the opposite direction equally hard.


Let's study how a rocket works to understand
Newton's Third Law. 

The rocket's action is to push down on the ground with the force of its powerful engines, and thereaction is that the ground pushes the rocket upwards with an equal force.

UP,
UP,
and
AWAY!

Third Law

The third law says that for every action (force) there is an equal and opposite reaction (force). 

Forces are found in pairs. Think about the time you sit in a chair. Your body exerts a force downward and that chair needs to exert an equal force upward or the chair will collapse. It's an issue of symmetry. 
Acting forces encounter other forces in the opposite direction. 

There's also the example of shooting a cannonball. 
When the cannonball is fired through the air (by the explosion), the cannon is pushed backward. The force pushing the ball out was equal to the force pushing the cannon back, but the effect on the cannon is less noticeable because it has a much larger mass. That example is similar to the kick when a gun fires a bullet forward. 

Write out the questions 1-8 on notebook paper & answer each question with details.  Turn in when done.  You may use your notes to help you with answers.   DUE:  10/14 1. Who was the scientist who gave us the Laws of Motion? 2. How many Laws of Motion are there? 3. What is another name for the first law of motion? 4. Which law explains why we need to wear seatbelts? 5. Which law says that force is equal to mass times acceleration (F=MA)? 6. Which law says that heavier objects require more force than lighter objects to move or accelerate them? 7. Which law explains how rockets are launched into space? 8. Which law says that for every action there is an equal and opposite reaction?

REVIEW OF NEWTON'S LAWS OF MOTION

Newton’s laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motion due to those forces. They have been expressed in several different ways over nearly three centuries, and can be summarized as follows:

1. First law: The velocity of a body remains constant unless the body is acted upon by an external force.

2. Second law: The acceleration a of a body is parallel and directly proportional to the net force F and inversely proportional to the mass m, i.e., F = ma.

3. Third law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear.

PHYSICS - VIDEO CLIPS

Review these video clips & ADD information you need to your notes.

SIMPLE MACHINES

FORCE & MOTION

GRAVITY & INERTIA

NEWTON'S 1ST LAW OF INERTIA

NEWTON'S 2ND LAW:  ACCELERATION

NEWTON'S 3RD LAW:  ACTION & REACTION