Why school bags have wide straps?

Answer 1

A wider strap distributes the force throughout a greater surface area. You can do a comparison using a simple physics equation.
Pressure = Force/Area

So take two different straps and measure the area of them.
Then find out how much weight the pack will be holding.
Then divide the Weight by the Area and you end up with pressure.

If you're into physics then you'll want to think about mass times accelaration but normally weighing your books on a scale will do.

So here's an example.

Lets say you have two straps. One is 1 inch by 6 inches
and the second is 3 inches by 6 inches

Now you have 5 lbs of books (I think that's alot if you're a kid)

so the pressure on your shoulders using the first strap is:

10 lbs/(1" X 6") = 1.67 lbs/inch squared or PSI

Now for the second strap:

10lbs/(3"X6") = .55 lbs/inch sqared or PSI

This means that for every inch of your skin that is touching the strap, the first one has more than one pound of force on it than the other.

So that's a more mathematical approach to why shcool bags have wide straps: Better weight distribution in the shoulders.

Answer 2

To balance the weight on your shoulder blades. These muscles that hold the straps are connected to your muscles in your neck, and if they have too much pressure put on them, you can easily get a headache from the muscle tension.

Answer 3

So that the pressure that is exerted on your shoulder would be less...if you have thin straps for your school bag...your shoulders will hurt! its the same theory when you are carrying a plastic bag or something...

Answer 4

holds the weight better on your shoulders like bras the bigger the boobs the bigger the straps you need.