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Please help! Urgent

My physics exam is tomorow and i did the specimen paper today and im completely stuck on this question. i thought i knew how to do it but what i did was completely different to the ans on the MS

please can someone explain this to me!
thank you

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Reply 1

samb1234

Original post by Exotic-L

Resolve horizontally, remembering that the tension in each part of the string is the same

Reply 2

Exotic-L

Original post by samb1234

Resolve horizontally, remembering that the tension in each part of the string is the same

thanks for the reply,
could u show me ur working please

Reply 3

samb1234

Original post by Exotic-L

thanks for the reply,
could u show me ur working please

I'm not going to do the question for you, as you need to be able to do this for yourself in the exam. Think about what component of the tension will be acting in the horizontal direction

Reply 4

moiziqfam

Draw your triangle and think about how the 800 force affects the arrow and THEN put the force into the triangle. Never confuse your self by thinking to much. And could you tell me where this question is from, I would like to try some like these.

Reply 5

moiziqfam

Are you doing AQA. I have physics tomorrow as well, nervous af

Reply 6

Exotic-L

Original post by moiziqfam

thanks for the reply, im doing WJEC and its from the specimen paper for the newspec. when i do the triangle, to find the resultant force, i would need the vertical component, and i dont know where to put the angle. thats what i dont understand. i think ive been over thinking and now ive just confused myself

Reply 7

Exotic-L

Original post by samb1234

Resolve horizontally, remembering that the tension in each part of the string is the same

resolving horizontally is Fcos(70) but i dont understand the tension bit.
i think ive over complicated this and now ive confused myself

Reply 8

samb1234

Original post by Exotic-L

resolving horizontally is Fcos(70) but i dont understand the tension bit.
i think ive over complicated this and now ive confused myself

We know that the tension in each half of the string is T, and we know that the total horizontal component is 800N. So we can see that 2Tcos70=800

Reply 9

Exotic-L

Original post by moiziqfam

Are you doing AQA. I have physics tomorrow as well, nervous af

i think i know im gonna fail, nd ive given up all hope for physics!!
ive done soo much that nothing is going in and i cant understand anything anymore im brain dead atm. its worrying me :s-smilie:

Reply 10

Exotic-L

Original post by samb1234

We know that the tension in each half of the string is T, and we know that the total horizontal component is 800N. So we can see that 2Tcos70=800

so when a force acts on a string, u think of the string as divided by 2?

Reply 11

samb1234

Original post by Exotic-L

so when a force acts on a string, u think of the string as divided by 2?

In this case yes

Reply 12

moiziqfam

Original post by Exotic-L

You do not need to vertical force. You have the horizontal force. To make things simpler. I will tell u this the forward force is going to be 400 NOT 800 as it is being split into two bow strings. (Newtons third law, every object has equal or opposite reaction). Since the forward force is 400, you know the angle now its basic trig to get the Tension.

if you still dont get the answer only then see my working. I advise you to try it first,.

Forward reaction(horizontal) = 400N
T is the hypotenuse so using trig, T cos 70 = 400, T =1169.52