# Vector question help A2

Watch
Announcements
#1
Hi,
In the question below i keep checking my working and can't find a mistake with my numbers so i'm assuming my method's flawed?
Thank you

Last edited by Rhys_M; 1 month ago
0
1 month ago
#2
The 625 should be 25. The magnitude of a is 5, so a^2 = 25.
Last edited by mqb2766; 1 month ago
0
#3
(Original post by mqb2766)
The 625 should be 25. The magnitude of a is 5, so a^2 = 25
But the vectors i'm adding to give the resultant are forces, so i need to equal it to the magnitude of the force, not acceleration, don't I?
(Using f=ma)
If not then why would they give me the mass?
0
1 month ago
#4
Yes, missed the mass part. Just skim read the acceleration.
What does the model solution give?
Last edited by mqb2766; 1 month ago
0
#5
(Original post by mqb2766)
Yes, missed the mass part. Just skim read the acceleration.
What does the model solution give?
There's not a worked solution but the MS just says -7/3 and -3
0
1 month ago
#6
-3 gives a force of magnitude 5. I guess -7/3 does the same, so your soln is correct, they;ve probably calculated witen the force has magnitude 5.
Note the -3 solution corresponds to a 3 : 4:5 triangle.
Last edited by mqb2766; 1 month ago
0
#7
(Original post by mqb2766)
-3 gives a force of magnitude 5. I guess -7/3 does the same, so your soln is correct, they;ve probably calculated witen the force has magnitude 5.
Note the -3 solution corresponds to a 35 triangle.
Thank you
0
#8
(Original post by Rhys_M)
Thank you
There's another question of the same type to which I also get a wrong answer VVVV
Do you think the book has a systematic error?
0
1 month ago
#9
Not sure what the solution is, but your +10 isnt correct.
Sub the book answer and your corrected answer into the F = .. expression and you should be able to work out which is correct?
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### What support do you need with your UCAS application?

I need help researching unis (20)
14.18%
I need help researching courses (8)
5.67%
I need help with filling out the application form (7)
4.96%
I need help with my personal statement (57)
40.43%
I need help with understanding how to make my application stand out (36)
25.53%
I need help with something else (let us know in the thread!) (3)
2.13%
I'm feeling confident about my application and don't need any help at the moment (10)
7.09%