Have you ever wondered!

Why do we normally swing our hands while walking and why not when we carry a load in our hands?

  • The center of gravity of a body depends on the distribution of mass in the body. When we walk, the movement of the legs tends to cause a shift in the center of the gravity of the body. To compensate this shift we swing our hands. When we are carrying a load in the hands, however, the effective center of gravity is lower, making it easier to maintain the balance.

How does a kingfisher catch fish?

  • The kingfisher flies vertically over the position of the fish, then plunges into water at 9090^\circ angle. The notion here is that normal incident rays do not undergo refraction, hence the fish lies exactly where it appears to be. At any other angle than9090^\circ, the apparent location of the fish would be different from its real location.

Why does the salt become damp when kept exposed during the rainy season and not when exposed during summer season?

  • In the rainy season humidity in the atmosphere is very high, then calcium chloride (CaCl) which is an impurity in the common salt, absorbs this moisture and makes the salt damp. In summer as the temperature is high, calcium chloride tends to loose moisture through the process of evaporation and the salt is left free-flowing.

More explanation/more relevant answers are welcomed! Please share if you have any.

  • If you have any such question based on facts or fun or wonder, post them in the comments and enjoy the discussion. ..

Note by Sandeep Bhardwaj
5 years, 11 months ago

No vote yet
1 vote

  Easy Math Editor

This discussion board is a place to discuss our Daily Challenges and the math and science related to those challenges. Explanations are more than just a solution — they should explain the steps and thinking strategies that you used to obtain the solution. Comments should further the discussion of math and science.

When posting on Brilliant:

  • Use the emojis to react to an explanation, whether you're congratulating a job well done , or just really confused .
  • Ask specific questions about the challenge or the steps in somebody's explanation. Well-posed questions can add a lot to the discussion, but posting "I don't understand!" doesn't help anyone.
  • Try to contribute something new to the discussion, whether it is an extension, generalization or other idea related to the challenge.
  • Stay on topic — we're all here to learn more about math and science, not to hear about your favorite get-rich-quick scheme or current world events.

MarkdownAppears as
*italics* or _italics_ italics
**bold** or __bold__ bold

- bulleted
- list

  • bulleted
  • list

1. numbered
2. list

  1. numbered
  2. list
Note: you must add a full line of space before and after lists for them to show up correctly
paragraph 1

paragraph 2

paragraph 1

paragraph 2

[example link](https://brilliant.org)example link
> This is a quote
This is a quote
    # I indented these lines
    # 4 spaces, and now they show
    # up as a code block.

    print "hello world"
# I indented these lines
# 4 spaces, and now they show
# up as a code block.

print "hello world"
MathAppears as
Remember to wrap math in \( ... \) or \[ ... \] to ensure proper formatting.
2 \times 3 2×3 2 \times 3
2^{34} 234 2^{34}
a_{i-1} ai1 a_{i-1}
\frac{2}{3} 23 \frac{2}{3}
\sqrt{2} 2 \sqrt{2}
\sum_{i=1}^3 i=13 \sum_{i=1}^3
\sin \theta sinθ \sin \theta
\boxed{123} 123 \boxed{123}


Sort by:

Top Newest

Regarding why our arms swing when we walk, I propose that experiments be done with robots that sort of look like humans, but have "arms" dangling loosely on the sides. I would bet that when such robots walk like how we do, their arms will naturally start to swing like pendulums, as a consequence of the walking action, which is far from smooth. Furthermore, I say that the more likely outcome is for arms to swing in opposite cadence with our legs. When we attempt to suppress such swinging movement of our arms, we actually have to work a bit extra, and we don't like having to work any more than we have to. Ergo, we just let our dangling arms swing as we walk.

As an analogy, and to illustrate my point, an experiment has been done with two identical pendulum clocks that have been bolted onto to a common back board, so that they are clicking side by side, at some distance from each other. The only mechanical influence they have on each other is slight vibrations sent down the back board, caused by the swinging of the pendulum. Quite invariably, given enough time, the pendulums start to swing in exact synchrony, but in opposite directions. Kind of like how our arms end up doing while walking "naturally".

Michael Mendrin - 5 years, 11 months ago

Log in to reply

That reminds me of the "pendulums placed side by side". Problem upcoming ...

Calvin Lin Staff - 5 years, 11 months ago

Log in to reply

A pheasant sits with the back towards the wind-flow. Think, think, think. Why? Pheasants are mostly stinking. They hide themselves under the bushes but cannot hide the stink. They know that a predator will attack from the direction after smelling them.

Rajen Kapur - 5 years, 11 months ago

Log in to reply


Problem Loading...

Note Loading...

Set Loading...