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Higher Physics 2013-2014

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Reply 60
Original post by CSM1996
Hmm idk, try posting a picture of the diagram, it might help the person who is able to help you :tongue:


Parallel weight . . .


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Original post by Pennyarcade
Ive had a mind blank and I completely cant remember how to do this one:
Two boys are pulling a car of mass 800 kg
along a level surface with a pair of ropes attached
horizontally as shown below. (both ropes being pulled at 20 degrees from the dotted line in separate directions)
When the pull on each rope is 400 N in the
directions indicated, the acceleration of the car is
0.1ms-1
.
What is the size of the frictional force acting on

the car in the above situation?

A 194N
B 434 N
C 533N
D 672 N
E 832N
thanks.



Use the unbalanced force parallel to the horizontal.

I don't know how to put something in a spoiler but this should help if you're not sure.

Fun=ma

F - friction = ma, where F is the force parallel which is "force at an angle x cos(angle to the horizontal)"


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Original post by FizzicsGuy
Use the unbalanced force parallel to the horizontal.

I don't know how to put something in a spoiler but this should help if you're not sure.

Fun=ma

F - friction = ma, where F is the force parallel which is "force at an angle x cos(angle to the horizontal)"


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Yeah I just did that and I got an answer of 375.89 :confused:
Original post by Pennyarcade
Yeah I just did that and I got an answer of 375.89 :confused:


It's late and I've done it quickly, but there is TWO ropes pulling at 400N. Did you account for that?
Original post by TheFOMaster
It's late and I've done it quickly, but there is TWO ropes pulling at 400N. Did you account for that?


Original post by FizzicsGuy
Use the unbalanced force parallel to the horizontal.

I don't know how to put something in a spoiler but this should help if you're not sure.

Fun=ma

F - friction = ma, where F is the force parallel which is "force at an angle x cos(angle to the horizontal)"


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I ended up getting it, my calculator was just being a weirdo :rolleyes:
Reply 65
I don't know how to do this question I've attempted it and my workingImageUploadedByStudent Room1379423460.574869.jpg is below but I got the answer wrong


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Reply 66
ImageUploadedByStudent Room1379423526.874940.jpg

(Uploaded in two parts by mistake oops)


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Wooo got 15/16 in my physics test :biggrin:

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ImageUploadedByStudent Room1381071526.927589.jpg can anyone help me with 3.42 thanks in advance :smile:


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Original post by Ewan-Hunter
ImageUploadedByStudent Room1381071526.927589.jpg can anyone help me with 3.42 thanks in advance :smile:


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Use your knowledge to establish the relationship between voltage and light intensity. If the light intensity is proportional to the light output, then with a higher light intensity you'll get a brighter bulb. Would this mean a higher or lower voltage is required?

Spoiler

Thanks very much, got it :smile:


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Reply 73
The driver of a car travelling along a level road brakes sharply. The from wheels of the car lock producing the skid marks shows below* as the car comes to rest
(The diagram basically shows that the mark was 32.2m long)
The mass of the car including the driver is 1050kg. It is estimates that the frictional force while skidding is 5210N.
Calculate the speed of the car just before it's wheels looked.

I calculated the acceleration first. which is a=F/m= 4.96ms-1
I then wanted to use one of the equations of motion to work out the time and then use s=d/t to calculate the speed but I don't know what 'u' and 'v' is. What should I do? Thanks
Original post by Delenelie
The driver of a car travelling along a level road brakes sharply. The from wheels of the car lock producing the skid marks shows below* as the car comes to rest
(The diagram basically shows that the mark was 32.2m long)
The mass of the car including the driver is 1050kg. It is estimates that the frictional force while skidding is 5210N.
Calculate the speed of the car just before it's wheels looked.

I calculated the acceleration first. which is a=F/m= 4.96ms-1
I then wanted to use one of the equations of motion to work out the time and then use s=d/t to calculate the speed but I don't know what 'u' and 'v' is. What should I do? Thanks


s=d/t assumes constant speed, but the car is decelerating.

In this case, we know he decelerates to rest, so what is the final velocity, v? We know the deceleration (from the frictional force and mass).
We are trying to work out his initial velocity, u.
Reply 75
Original post by Asklepios
s=d/t assumes constant speed, but the car is decelerating.

In this case, we know he decelerates to rest, so what is the final velocity, v? We know the deceleration (from the frictional force and mass).
We are trying to work out his initial velocity, u.

I get it now :smile: Thank you
Reply 76
image.jpg help!!
Reply 77
A ball is thrown horizontally from the window of a building with velocity 12 m s-1. The window is 30 m above the ground.
Calculate the horizontal distance between the building and the point where the ball hits the ground.

Anyone? I assume I need to use the equations of motion?
Reply 78
Original post by Delenelie
Anyone? I assume I need to use the equations of motion?


Yes you do. Just remember to keep the vertical and horizontal values separate.
Reply 79
I have my unit 1 NAB on Wednesday and my A/B test on Wednesday, not going to be a good day considering I've not really been doing well in physics :lol:

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