basic trigonometry confusion, need help

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theguywhosaidhi
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QP = http://filestore.aqa.org.uk/subjects...2-QP-JUN14.PDF
MS = http://filestore.aqa.org.uk/subjects...W-MS-JUN14.PDF

this is question 1a) and I get that obviously weight is (mass * 9.81) but then you are working out the slanted force. So I did (mass * 9.81) / sin25 as its opposite/hypotenuse, but the mark scheme says to multiply the weight by sin25. It's very basic and fundamental, I know, but if you can spare sometime to explain I'd really appreciate it. thanks =]
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JustDynamite
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Do you do Mechanics in maths? Its the same thing as when you split the force into two components, one going along the slope and one going perpendicular to the slope. So the force acting down the slope will be mgsin25 and the component acting perpendicular to the slope will be mgcos25
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theguywhosaidhi
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(Original post by JustDynamite)
Do you do Mechanics in maths? Its the same thing as when you split the force into two components, one going along the slope and one going perpendicular to the slope. So the force acting down the slope will be mgsin25 and the component acting perpendicular to the slope will be mgcos25
does weight act perpendicularly down from the slope or does it work straight down from any point on the slope? and we do decision 1 for our first year, statistics 1 next year
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Vikingninja
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(Original post by theguywhosaidhi)
does weight act perpendicularly down from the slope or does it work straight down from any point on the slope? and we do decision 1 for our first year, statistics 1 next year
Weight is always vertically downwards.

When I was in AS what we were taught was to draw the slope triangle but then draw a triangle within it where the hypotenuse is the force by the weight, and the opposite to the angle was the force down the slope.

So then it would be weight x sin25.


Reason for this is that the weight is the largest force so should be the hypotenuse. The force down slope is due to the weight but should be smaller.
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JustDynamite
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(Original post by theguywhosaidhi)
does weight act perpendicularly down from the slope or does it work straight down from any point on the slope? and we do decision 1 for our first year, statistics 1 next year
Yeah, so you would have the weight going downwards and because its at an angle of 25 degrees. You would split the weight into two components one going along the slope downwards which is mgsin25 and one that's going perpendicular to the slope which is mgcos25.
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theguywhosaidhi
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(Original post by Vikingninja)
Weight is always vertically downwards.

When I was in AS what we were taught was to draw the slope triangle but then draw a triangle within it where the hypotenuse is the force by the weight, and the opposite to the angle was the force down the slope.

So then it would be weight x sin25.


Reason for this is that the weight is the largest force so should be the hypotenuse. The force down slope is due to the weight but should be smaller.
hi, so like the image I've drawn? That helps a lot, I remember seeing this but I'm not sure why the smaller triangle has the 25 degrees where it is
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