# Maths Vectors Question A Level

Watch
Announcements
#1
Hi, I am REALLY struggling on this question and dont know where to even begin, any help would be great!

The horizontal unit vectors i and j are in the directions east and north respectively.

A model ship of mass 2kg is moving so that its acceleration vector ams^-2 at time t seconds is given by

a=3(2t-5)i+4j. When t=T, the magnitude of the horizontal force acting on the ship is 10N.

Find the possible values of T.

Ive been told to use pythagorus to find the magnitude of the corresponding force and equate to 10 and solve for T. But unfortunately I do not know what that means so if someone could explain in simpler terms it would be much appreciated!!!! <3
0
4 weeks ago
#2
(Original post by hayley26)
Hi, I am REALLY struggling on this question and dont know where to even begin, any help would be great!

The horizontal unit vectors i and j are in the directions east and north respectively.

A model ship of mass 2kg is moving so that its acceleration vector ams^-2 at time t seconds is given by

a=3(2t-5)i+4j. When t=T, the magnitude of the horizontal force acting on the ship is 10N.

Find the possible values of T.

Ive been told to use pythagorus to find the magnitude of the corresponding force and equate to 10 and solve for T. But unfortunately I do not know what that means so if someone could explain in simpler terms it would be much appreciated!!!! <3
Force = mass x acceleration. If you have the magnitude of the force you can find the magnitude of acceleration. How do you get the magnitude of a vector when you know its i- and j- compnents?
0
#3
using pythagorus - but when finding magnitude e.g. (sqr root) (6t-15)^2 + 4^2 , do i ignore the t ?
0
3 weeks ago
#4
(Original post by hayley26)
using pythagorus - but when finding magnitude e.g. (sqr root) (6t-15)^2 + 4^2 , do i ignore the t ?
The problem is to solve for the time when the acceleration corresponds to a force of 10N.
How are force and acceleration related? Then solve for t.

Note, your pythagorean triples could give you a short cut way to the answer(s), but setting up the problem as a quadratic in t is the usual method.
Last edited by mqb2766; 3 weeks ago
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

Yes, and I've sent off my application! (216)
56.4%
I've made my choices but havent sent my application yet (50)
13.05%
I've got a good idea about the choices I want to make (44)
11.49%
I'm researching but still not sure which universities I want to apply to (33)
8.62%
I haven't started researching yet (23)
6.01%
Something else (let us know in the thread!) (17)
4.44%