by Ron Kurtus
Readers have sent in a total of 166 comments and questions on Experiments issues. They are listed according to date.
You can read them to further your understanding of the subject.
|Measuring weight in water doesn't seem to work||Fluids||USA|
|Static electricity and hair color||Static Electricity||USA|
|Questions would help learning||Fluids||Vanuatu|
|Does fiction depend on area of contact?||Friction||Philippines|
|Experiment to determine center of gravity||General||Uganda|
|Aluminum strips don't seem to work||Electroscope||India|
|I want simple projects||Electroscope||India|
|Understanding friction theory||Friction||Nigeria|
|Boiling water in a plastic container||Heat||Nigeria|
|Report on determination of coefficient of static friction||Friction||USA|
|How water affects sound waves||Sound Amplified Over Water||USA|
|How does electroscope detect charges?||Electroscope||USA|
|Experment to produce water waves||Waves||India|
|Making a working model of a coal mine||General||India|
Measuring weight in water doesn't seem to work
March 8, 2014
Hello! I am doing this experiment with my first grade son and all of the items are weighing the exact same in and out of the water! We had assumed that they would for sure weigh less in the water when they are sinking and displacing the water above. We have tried heavier objects, larger objects, and other variations and no matter what I use the results are the same: the rock is weighing 4.6 oz on land and 4.6 oz totally submerged in water. Am I missing something? My son badly wants to be a scientist and I don't want to lead him down a wrong path of understanding science just because I'm doing something wrong! He wanted to do this due to his curiosity of why he can lift his brother in the pool but not on land. ANY help would be so much appreciated!
Megan - USA (24589)
The best way to weigh the rock is to hang it by some string from a spring scale or something similar both in air and in the water. There should be a difference in weight. Otherwise, I'm not sure why you are getting the same weight in and out of the water.
I will have to add a drawing to the experiment to clarify the method.
It is good that your son is curious, because that it the first step in becoming a scientist.
Static electricity and hair color
November 30, 2013
My name is Mrs. Latoya Bush, I have a nine year old daughter who is doing a science fair project on static electricity and hair color, and would like to get information and use it for as a resource.
1. can you please explain static electricity?
Johnae - USA (24235)
See Controlling Flyaway Hair from Static Electricity for information about the subject. Your daughter should be able to understand the material.
By brushing or combing a person's hair with a plastic comb, you can create static electricity. Red hair is usually very fine and results in flyaway hair more that thicker hair, such as black hair.
I hope that helps. Best wishes on her project.
Questions would help learning
November 1, 2013
this experiment is very good and it works. do you think that this will help the students if there are no questions that will contribute to the students learning and understanding? Excuse my poor English
kathrian - Vanuatu (24160)
Thank you for your suggestion. I will be adding questions and answers to the various experiments, in order to help the students learn and understand the material.
Does fiction depend on area of contact?
July 24, 2013
Does frictional force depend on the area of contract?
Roberto - Philippines (23884)
For hard flat surfaces, the resistance force of friction is independent of the area of contact. See Standard Friction Equation for information.
However, most surfaces are not perfectly flat or hard. Variations will result in area of contact having a contribution.
Studying how friction varies with pressure, area, and flatness would be a good set of experiments.
Experiment to determine center of gravity
July 22, 2013
I WANT AN EXPERIMENT TO DETERNIME THE CENTER OF GRAVITY
WASSWA - Uganda (23880)
See Center of Gravity for an explanation and pictures.
You can then devise an experiment to fine the center of gravity in other objects.
Aluminum strips don't seem to work
July 17, 2013
With due respect , I beg to say that while making eletro-scope I dealed with a problem .My problem is that while making it can we use aluminum foil strips instead of metal strips .... I tried it several times with aluominum strips ,but no results...
Please help me to make it ..
simran - India (23868)
Thin aluminized Mylar (plastic) strips should work as the foil strips. Aluminum foil may sometimes be too thick to work properly.
See Home Made Electroscopee for some good instructions.
Best wishes with your experiment.
March 30, 2013
Didn't know if you were taking suggestions for new resources to list on the Resources on Science Projects and Experiments page of your website, but if you are, I recently came across something that might be worth adding. If you're interested in taking a look, let me know and I'll send over the details. If not, then don't worry about it.
Jon - USA (23570)
Thanks for the offer. I'd be glad to see some new resources.
I want simple projects
March 3, 2013
i want more best and simple projects
Anshu - India (23517)
We will be adding more project soon.
Understanding friction theory
February 27, 2013
i was give an experiment based on the coefficient of static friction. I'm done with the experiment but writing the theory is what i can't do. Can you help me with the theory based on the experiment(coefficient of static friction )
chibuike - Nigeria (23502)
The equation for friction force is Fr = ¼N. However, the value of the coefficient of friction (¼) is different for static and sliding friction, the with static coefficient being higher.
See Standard Friction Equation for more information.
Also Measure Coefficient of Friction with a Ramp may help you.
I hope this helps you understand the principles. Look at the other Friction lessons for more information.
Boiling water in a plastic container
February 18, 2013
I boiled some water(up to 100C ) in a plastic kettle on a gas cooker and the kettle does not melt. Please explain to me the science behind this process.
Abu - Nigeria (23207)
It is a very clever experiment. The reason the plastic does not melt is because the water absorbs the heat better than the plastic. This means that the temperature of the water and the plastic stays the same as the temperature of the water increases. However, once the water starts to boil, the temperature of the steam can quickly go beyond 100C such that the pastic may start to melt.
This same experiment is often done with a cardboard container over a fire. The cardboard will not burn as the water is heated up.
Report on determination of coefficient of static friction
January 27, 2013
how can we write a report on determination of coefficient of static friction between a cardboard box and a wooden bench?
- USA (23155)
You usually need a spring scale to measure the force required to start the movement of the box. It is better to have some weight in the box, so that the scale will have a reading. Then the coefficient of friction will be the force reading on the spring scale divided by the weight of the box and its contents.
In your report, state your goal, the equipment used, and the steps you take to perform the experiment. Then record a series of readings and take the average results.
I hope this helps you write up your project report.
How water affects sound waves
January 8, 2013
My 11 year old son is doing a science project on how water affects the speed of sound and he found this article very interesting. He would like to know if you have any ideas or suggestions on a science experiment he could do to show this information. Unfortunately we live were it is currently winter so all the bodies of water nearby are currently frozen, but any suggestions you may have would be greatly appreciated.
Jennifer - USA (23114)
When sound travels over a body of water, the effect is from the water cooling the air. So, it is not a case of water affecting the speed of sound directly.
Sound should travel faster in ice than in air. If you hit the lake ice with a hammer a distance away and had your ear against the ice, you should be able to hear the difference in sound reaching you. (However, it could be real cold on your ear.)
A similar experiment is done in a large swimming pool by having an ear in the water and the other outside the water, and clicking two objects together.
Of course, for both of these experiments, using microphones to detect the sound would be better, provided you could compare the times.
These ideas may not be practical, but hopefully they'll give you some ideas.
Best wishes for success in his science project.
How does electroscope detect charges?
January 4, 2013
What happened to the object when you rubbed the balloon with wool?
How did the device you made detect static electricity?
Sofia - USA (23104)
The wool loses some electrons to the balloon, while the balloon gains negative charges.
The way the electroscope detects the charges involves a number of steps:
When you put the balloon near the electroscope, the charges on the balloon cause the metal end of the electroscope to gain positive charges. This in turn gives the same charge to the leaves and causes them to repel each other.
See Detection of Static Electricity for more information.
Experment to produce water waves
November 15, 2012
GOAL- TO PRODUCE WAVES & STUDY THEIR PROPERTIES
MATERIALS- A 9 VOLT BATTERY
A WOODEN BOARD
A 12 VOLT MOTOR
A RUBBER BAND
A THREAD SPOOL
SMALL PIECES OF PAPER
A WOODEN ROD WITH A HOOK
1. TAKE THE WOODEN BOARD AND THEN FIX THE MOTOR AND THE BATTERY ON THE BOARD BY USING THE SWITCH(KEEP THE SWITCH IN A OFF POSITION)
2.NOW TAKE THE THREAD SPOOL AND FIX IT ON THE MOTOR AND TIGHTEN IT BY KEEPING SOME SMALL PIECES OF PAPER(KEEP THE SPOOL ON THE METALIC ROD THAT PEEPS OUT OF THE MOTOR AND THEN TIGHTEN IT)
3.NOW HANG THE WOODEN ROD ON THE SPOOL WITH THE HELP OF A STRING
4.NOW SWITCH ON THE MOTOR , CIRCULAR WAVES WILL BE GENERATED
5.KEEP A SMALL PIECE OF PAPER AND GIVE THE CONCLUSION THAT THE WAVES OF A WATER DOES NOT MAVE FORWARD (INSTEAD ONLY GIVE A UP AND DOWN MOVEMENT)
ROUNAK - India (23037)
Thank you for the information on an experiment to create waves. I will be adding it to our experiments soon.
Best wishes in your science studies.
Making a working model of a coal mine
September 28, 2012
I want to make a working model on coal mines. Please guide me of suggest any other interesting working model.
Anubhav - India (22964)
You can make a model of a coal mine by showing its insides with a frame that has glass or plexiglass to show the tunnels and such. You can use regular dirt, but you must have black material or even coal to show where the workers would be digging.
It would be very difficult to make a working model, since you would need model trains and digging machines inside your model. It is better to show what the inside of a coal mine looks like and then show pictures of what the workers do to get out the coal.
Best wishes in your project.
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