questions concerning measurements, experiments, and activities that demonstrate physics and are safe to do at home, require at most one tool or ingredient not readily available, and can be interpreted or analyzed on one sheet of paper with accessible math.

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358
votes
19answers
133k views

Cooling a cup of coffee with help of a spoon

During the breakfast with my colleagues, a question popped into my head: What is the fastest method to cool a cup of coffee, if your only available instrument is a spoon? A qualitative answer would ...
36
votes
13answers
9k views

Home experiments to derive the speed of light?

Are there any experiments I can do to derive the speed of light with only common household tools?
200
votes
4answers
36k views

Can I compute the mass of a coin based on the sound of its fall?

Other day, I bumped my bookshelf and a coin fell down. This gave me an idea. Is it possible to compute the mass of a coin, based on the sound emitted when it falls? I think that there should be a ...
11
votes
2answers
452 views

The secret behind the spinning, asymmetrically weighted, 2D disk-shaped top?

When you spin an asymmetrically weighted, 2D disk-shaped top, the heavy part actually rises to the top. Why is this? http://www.youtube.com/watch?v=h0SZZTBQmEs ...
5
votes
2answers
1k views

Black hole analog experiment?

This question is directed mostly at people giving lectures on black holes, but input by other physicists or students is very much appreciated. Do you know a good (home)-experiment with a black hole ...
80
votes
24answers
9k views

How can you weigh your own head in an accurate way?

I read some methods but they're not accurate. They use the Archimedes principle and they assume uniform body density which of course is far from true. Others are silly like this one: Take a knife ...
10
votes
1answer
1k views

What are the specific requirements for a do-it-yourself quantum double-slit experiment?

I was shocked to recently learn that the double-slit experiment is not only possible to do with completely ordinary equipment (with photons of course), but it actually looks rather easy. This is from ...
19
votes
4answers
2k views

Why does a cork float to the side of a glass?

What is this physical phenomenon and when it's happen ? Please take a look at this picture: Link to picture Notice: This is a cork ball attracted to sides of a glass of water
5
votes
3answers
3k views

Atmospheric pressure experiment using a cup with a fluid to hold a glass plate

When I was in high school, my teacher did an experiment to show the power of atmospheric pressure. Experiment: Prepare a glass bottle, fill with water, put a glass plate on the bottle, make sure ...
5
votes
4answers
3k views

Is coherent light required for interference in Young's double slit experiment?

In this Veritasium video, a home experiment is presented which appears to produce a very good double-slit interference pattern with normal sunlight. The experiment is an empty cardboard box with a ...
5
votes
1answer
161 views

Why does separating plastic from a cough drop create flashes?

I was tearing open individually-wrapped cough drops in the dark, and noticed that when I pulled apart two adhesive-joined pieces of silvery plastic film, small flashes of light were produced. It was ...
18
votes
3answers
3k views

Why does the sound pitch increase on every consecutive tick at the bottom of a filled cup of coffee?

Since I don't know the proper physical terms for this, I describe it in everyday English. The following has kept me wondering for quite some time and so far I haven't found a reasonable explanation. ...
13
votes
6answers
4k views

Tried to do the double slit experiment, failed. Why?

I tried, and failed, to do the double-slit experiment. I thought I had a good experiment setup, but obviously I was wrong. Can anyone offer some insight in what I might have done wrong? Most of ...
2
votes
3answers
915 views

Apparent paradox in equation of continuity

Equation of continuity says us that if we insert some fluid in a tube, the same amount of fluid will come out from the other end. If we make a small hole in a hose pipe, water will come out with a ...
-6
votes
3answers
226 views

Can you lift a basket up while standing inside it? [closed]

Suppose you stand in a basket and you try to pull the handles of the basket. Will you be able to lift the basket from ground? Similarly, Baron M√ľnchhausen allegedly pulled himself and the horse on ...
1
vote
1answer
360 views

Are there good home experiments to get a feel for the behavior of yield-stress liquids?

What common household liquids / foodstuffs show Herschel-Bulkley fluid behavior? I assume tomato soup to be one, since when sloshing it around lightly on a spoon the visible surface moves as one (as ...
15
votes
4answers
2k views

How can I measure the mass of the Earth at home?

How can I measure the mass of the Earth at home? How was the mass of the Earth first measured?
12
votes
3answers
7k views

Is it possible to reproduce Double-slit experiment by myself at home?

I want to reproduce this experiment by myself. What I need for this. What parameters of slits and laser/another light source it needs? Is it possible to make DIY-detector?
25
votes
6answers
7k views

How do whisky stones keep your drink cold?

From a discussion in the DMZ (security stack exchange's chat room - a place where food and drink are important topics) we began to question the difference between how ice and whisky stones work to ...
18
votes
2answers
1k views

Why does blowing on a candle put it out but sucking doesn't?

Alternatively, why does the force created by blowing out air feel so much stronger than the force created by sucking in air? Ok, so forget the human factor involved in blowing out candles. Consider a ...
10
votes
3answers
1k views

How accurately can I expect to measure the gravitational constant with a club of college students?

I am a math instructor with almost no experimental physics background, but I run a math and engineering club that is interested in doing some experiments. I have read up a bit and see some obvious ...
10
votes
3answers
462 views

How can I weigh liquid in a sealed container?

How do you measure the mass and volume of alcohol if it is in a sealed container? Are there clever ways of achieving this? The weight of the container is not known. I can't open the container, I ...
8
votes
2answers
6k views

Does tea stay hotter with the milk in it?

A little thought experiment, similar to this one: Imagine you are making a cup of tea when the door bell rings. You've poured the boiling water into a cup with a teabag in it. As you're just about to ...
19
votes
2answers
1k views

Why does the note played by a flute not change in this case when the air column is interrupted?

I play the flute as a hobby, and I've noticed that when playing middle D or E flat, one can interrupt the air column by releasing a certain key (which is near the middle of the air column), and yet ...
14
votes
9answers
2k views

What are good mechanics experiments for 10 year olds? [closed]

I'm trying to explain elementary mechanics - without the benefits of calculus or even algebra - and struggling. I'd like to find reasonable ways to demonstrate Newton's laws, minimally, and possibly ...
9
votes
3answers
720 views

How hot is the water in the pot?

Question: How hot is the water in the pot? More precisely speaking, how can I get a temperature of the water as a function of time a priori? Background & My attempt: Recently I started spend ...
10
votes
6answers
5k views

How to measure resistance of a piece of wire?

My son is doing a science experiment on how varying temperature and diameter of wire impacts the resistance. We are assuming we can accomplish this by using different gauge wires, a home thermometer, ...
5
votes
1answer
351 views

Can you tell just from its gravity whether the Moon is above or below you?

If you are on a place of Earth where the Moon is currently directly above or directly below you, you experience a slightly reduced gravitational acceleration because of Moon's gravity. This is what ...
5
votes
5answers
6k views

Why does hot oil explode when pouring water on it?

I am puzzled to know, What is the reason of hot oil make sound and explode when we pouring water on it?
2
votes
1answer
2k views

Magnetic field strength in a solenoid

I'm pretty new to physics. I've been conducting some experiments with electromagnets. My practical results don't match up with the theory. The magnetic field in a solenoid of length $L$ around an ...
10
votes
3answers
801 views

Best way to chill a cup of coffee with cold water and 5 minutes [duplicate]

Initial data 1 x 3/4 full cup of hot coffee / tea / your favorite morning beverage cold water 5 minutes Considering that it's starting to get hot outside, and we all want to drink reasonably cold ...
6
votes
3answers
9k views

Why do lightbulbs continue to glow after the light is turned off?

I've noticed that whenever I turn the lamp off in my room at night, the lightbulb seems to continue to glow for a minute or so after that. It's not bright though; the only way I even notice it is if ...
5
votes
3answers
340 views

Home experiment question

I want to make a home experiment where I roughly explain the phenomenon of water remaining in a straw if you close one end of the straw. So I'm thinking that the weight of the water is pulling it ...
3
votes
1answer
2k views

Why is the lid of the cookware kept on induction cooker not hot?

Induction cookware cooks food by inducing an electro magnetic field in the ferro-magnetic cookware. Since iron offers a lot of resistance to the current, the current is converted into heat in the ...
1
vote
3answers
476 views

Beads in 'perpetual motion'?

This page has an interesting video of beads 'syphoning' out of a glass beaker: http://blog.zennioptical.com/weekly-optical-illusion-crazy-beads/ The host has a few explanations for the effect, but ...
0
votes
1answer
116 views

Why does shorting two cells in series heat them up?

I tried this with two 9V batteries that you can interlock easily and they heat up a lot. Why does this happen? The internal resistance of the batteries would be quite small so why would they still ...