Weight Of Your School Bag. (1 Viewer)

[lyounamu]

Hopefully your back doesn't strain

Don't worry. I may not sound (or look) like it but I can easily do weights and everything since I exercise about 2 hours a day.

 

[Forbidden.]

 

[lyounamu]

So how much force would I have to endure if I carry about 12 kg of weight on my back? (my bag that is)

 

[Forbidden.]

So how much force would I have to endure if I carry about 12 kg of weight on my back? (my bag that is)

Oh but these are the forces acting on the schoolbag.

The forces acting on you from the school are the forces of tension in the straps.
To simplify things I'll neglect the mass of the straps and assume you strapped your schoolbag so it isn't slumped and sits snugly on your back and the whole schoolbag including the straps acts as one whole mass.

Analysing in the y-direction to take into account the weight force.
ΣF_y = T sin 45 + T sin 45 - mg = ma (Newton's 2nd Law)
a_y = 0 with respect to the wearer.

T sin 45 + T sin 45 - mg = 0
2T sin 45 - mg = 0
T = mg / 2 sin 45 = (12kg)(9.8ms^-2) / 2 sin 45 = 61 N

m = F_weight/g = 61 N / 9.8ms^-2 = 6.22 kg

Health warning, potential distortion of chest bones in your body!
If you can't avoid wearing a 12kg bag, don't make your bag slumped downwards too much.
If you want add more straps in the same direction to spread out the tension lol.

 

[wendus]

my school bag is like 500 grams or less
what do you people carry in those things?!

 

[lyounamu]

Oh but these are the forces acting on the schoolbag.

The forces acting on you from the school are the forces of tension in the straps.
To simplify things I'll neglect the mass of the straps and assume you strapped your schoolbag so it isn't slumped and sits snugly on your back and the whole schoolbag including the straps acts as one whole mass.

Analysing in the y-direction to take into account the weight force.
ΣF_y = T sin 45 + T sin 45 - mg = ma (Newton's 2nd Law)
a_y = 0 with respect to the wearer.

T sin 45 + T sin 45 - mg = 0
2T sin 45 - mg = 0
T = mg / 2 sin 45 = (12kg)(9.8ms^-2) / 2 sin 45 = 61 N

m = F_weight/g = 61 N / 9.8ms^-2 = 6.22 kg

Health warning, potential distortion of chest bones in your body!
If you can't avoid wearing a 12kg bag, don't make your bag slumped downwards too much.
If you want add more straps in the same direction to spread out the tension lol.

Thanks for that, especially my own portrait.

I will get rid of all the unnecessary contents so that my bag can get less in weights. :uhhuh:

 

[Aerath]

You have got to be kidding me. Calculations?

 

[Forbidden.]

Thanks for that, especially my own portrait.

I will get rid of all the unnecessary contents so that my bag can get less in weights. :uhhuh:

I could have made you a uber sXc nerd featuring bowl-cut hair, glasses and pocket protector.
I save space and weight by carrying a satchel to uni (like those you use to carry laptops) and I rarely carry my 1500-page physics textbook.

You have got to be kidding me. Calculations?

That's REAL physics.

 

[Aerath]

That's REAL physics.

Thank god I'm not doing Phys in Uni.

 

[Aplus]

Thank god I'm not doing Phys in Uni.

It's basic Physics. Just using Newton's second law and notion of forces acting on an object. Since the bag is at rest in relation to the body, there is 0 force acting on it. Hence 0 acceleration.

 

[12o9]

ranges from 5-10kgs =)

 

[tahlzz]

my bag ranges from 7-12kg
which is really bad for your backs
=]

 

[rach19]

On a good day about 5-8kg's but I carry my folders and text books. Somedays I have 2 subjects and tafe others i'll have more.

 

[kaz1]

Nowadays probably 2-3kgs.

 

[nerdsforever]

everyone's gonna be hunchback

 

[lyounamu]

everyone's gonna be hunchback

It's a bit off the topic but,

nerdsforever: why do you have sad faces next to your future HSC subjects? You should choose subjects that you like.

 

[nerdsforever]

It's a bit off the topic but,

nerdsforever: why do you have sad faces next to your future HSC subjects? You should choose subjects that you like.

ohh the sad faces....It's because I dislike the subjects I will be doing.

English: I've never liked English in my life! I always get really bad marks

Studies of Religion: The school's gonna force me to take it because I need a one unit subject for 12 units. I was thinking of taking Biology because I like it and I do good in Biology related topics, but I cant have 13 units.

Chemistry: Mum has a friend who's daughter works in Pharmacy, so mum's forcing me to take chemistry. I'm taking Chemistry if mum let's me take Ancient History and she agreed

Economics: Just sounds complicated, but I'll survive :wave:

Yep. I should be choosing the subjects I like, so thats why I'll be choosing Ancient History, but my parents believe I need more high scaling subjects so I'll take Chemistry. Chemistry and Studies of Religion are really the two subjects I sorta dont want to take. Including English, but I dont have control over that.

 

[lyounamu]

ohh the sad faces....It's because I dislike the subjects I will be doing.

English: I've never liked English in my life! I always get really bad marks

Studies of Religion: The school's gonna force me to take it because I need a one unit subject for 12 units. I was thinking of taking Biology because I like it and I do good in Biology related topics, but I cant have 13 units.

Chemistry: Mum has a friend who's daughter works in Pharmacy, so mum's forcing me to take chemistry. I'm taking Chemistry if mum let's me take Ancient History and she agreed

Economics: Just sounds complicated, but I'll survive :wave:

Yep. I should be choosing the subjects I like, so thats why I'll be choosing Ancient History, but my parents believe I need more high scaling subjects so I'll take Chemistry. Chemistry and Studies of Religion are really the two subjects I sorta dont want to take. Including English, but I dont have control over that.

If you choose subjects that you won't like, the last 2 years of your schooling will eventually become the worst two years of your life. First, you will have to handle the stress coming from the subjects that you detest. Trust me - that's the worst feeling ever. Secondly, you will be forced to study for those subjects. Today, I had to suppress the overwhelming reaction coming from my mind while studying for Chemistry. (TWICE!) I nearly killed myself in the process and ended up sleeping for two hours. (totally unexpected waste of time)

Thirdly, it will affect your UAI and hence your Uni course selection. You do not seem to be aware of the effect that those 2 subjects may hold. 2 subjects = 4 units. I really suggest you to drop those subjects immediately next year if you find them either boring or challenging for you.

And your parents shouldn't be making decisions for you. I think you are mature enough to make judgements in regards to the HSC course selection and hence the future career that might be ahead of you.

 

[Caitlin63]

ohh the sad faces....It's because I dislike the subjects I will be doing.

English: I've never liked English in my life! I always get really bad marks

Studies of Religion: The school's gonna force me to take it because I need a one unit subject for 12 units. I was thinking of taking Biology because I like it and I do good in Biology related topics, but I cant have 13 units.

Chemistry: Mum has a friend who's daughter works in Pharmacy, so mum's forcing me to take chemistry. I'm taking Chemistry if mum let's me take Ancient History and she agreed

Economics: Just sounds complicated, but I'll survive :wave:

Yep. I should be choosing the subjects I like, so thats why I'll be choosing Ancient History, but my parents believe I need more high scaling subjects so I'll take Chemistry. Chemistry and Studies of Religion are really the two subjects I sorta dont want to take. Including English, but I dont have control over that.

Your school won't let you have 13 units???? Woah..... and I thought my school was shit. If you think you will like bio you should do it instead of chem, they are both science subjects so hopefully that will please your mum.

 

[BRUT]

My school bag is about 15 kg. No joke. I'm trying to get bigger shoulders, so it's all good.