IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: aiyla on November 20, 2009, 03:13:28 pm

Title: how to find resultant force of this question.
Post by: aiyla on November 20, 2009, 03:13:28 pm
Q) A ship is traveling st 5ms-1 with a bearing of 20 degree east of north. There is a current of 1ms-1 flowing from the west. What is the resultant velocity of the ship?


thanks
Title: Re: how to find resultant force of this question.
Post by: SGVaibhav on November 20, 2009, 03:23:22 pm
i was not sure about the answer so i just made a drawing :D
Title: Re: how to find resultant force of this question.
Post by: @d!_†oX!© on November 20, 2009, 03:36:30 pm
just make the 2 vectors using a scale on a graph paper or a plain paper....and the complete the parallelogram....the resultant  force will be the diagonal as in the diagram...the magnitude is the length of the diagonal and the direction is the angle between the 6ms-1 vector and diagonal....
Title: Re: how to find resultant force of this question.
Post by: staceyboy3 on November 20, 2009, 04:28:15 pm
Quote from: sgvaibhav on November 20, 2009, 03:23:22 pm
i was not sure about the answer so i just made a drawing :D

About the picture, the question says that the current is coming from the west. Your picture shows it coming from the east... :)
Title: Re: how to find resultant force of this question.
Post by: SGVaibhav on November 20, 2009, 04:35:26 pm
from  :D to  :(

lol
thanks for telling  ;D  (have to show teeth now)
Title: Re: how to find resultant force of this question.
Post by: aiyla on November 20, 2009, 05:50:42 pm
no clear answer yet ):
Title: Re: how to find resultant force of this question.
Post by: staceyboy3 on November 20, 2009, 09:13:52 pm
Ok, so the sh hasip velocity with northward component and eastward component.
The current only has eastward component.

First you want to find the magnitudes of the components, add them together and then use Pythagoras theorem to find the resultant.

Eastward component of velocity of boat: 5*sin20 = 1.710...

Add the component to the current: 1.71...+ 1 = 2.710...

You also need to find the northward component of the ship: 5*cos20 = 4.698...

Now use use Pythagoras theorem: R = sqr[(2.710...)^2 + (4.698...)^2] = 5.4240...

R is the resultant velocity, and sqr is square root
Title: Re: how to find resultant force of this question.
Post by: Ghost Of Highbury on November 21, 2009, 04:55:25 am
u can also try the attached method, its a relative velocity q By the way..

Title: Re: how to find resultant force of this question.
Post by: staceyboy3 on November 22, 2009, 12:11:29 pm
I like the way A@di did it. Neat formula :D
Title: Re: how to find resultant force of this question.
Post by: ilmarien on November 23, 2009, 08:47:30 am
Quote from: sgvaibhav on November 20, 2009, 03:23:22 pm
i was not sure about the answer so i just made a drawing :D
]

If only my teacher would allow an answer like that.  :-\
 ;D ;D
Title: Re: how to find resultant force of this question.
Post by: Ghost Of Highbury on November 28, 2009, 09:16:40 am
Quote from: staceyboy3 on November 22, 2009, 12:11:29 pm
I like the way A@di did it. Neat formula :D

thanks.. :)