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Physics please help!

http://www.rewardinglearning.org.uk/common/includes/microsite_doc_link.aspx?docid=10780-1

this is a past paper can someone please explain to me fully question 3 a and 3 c
3a:
Vectors have direction. Displacement is a vector. Distance is a scalar.
Therefore displacement has both magnitude and direction. Distance only has magnitude.
3bi:
s = vt
t = s/v
t = 114/171
t = 0.667h(3sf)

3bii:
There is a wind velocity acting at 160o. The net velocity is still at 250o.
The component of the plane's velocity acting opposite to 160o must be 36kmh-1. Therefore you can make a vector triangle.(draw a diagram)
v2 = 1712 + 362
v2 = 30537
v = 175kmh-1(3sf)
The angle will be tan-1(36/171) = 11.9o(3sf)
3 (a) (b)
(c)
Displacement has an implied direction, distance doesn’t
107 km
39.0 km
South and West matched to magnitudes (180° and 270°)
(i) Journey time = 23 hour (accept 40 min) (ii)v1712+362
175 (km h–1) Direction = 12°

That's the mark scheme but how do you get 107 and 39?
You've done a and c but how to do b?
Original post by BigDreamer123
3 (a) (b)
(c)
Displacement has an implied direction, distance doesn’t
107 km
39.0 km
South and West matched to magnitudes (180° and 270°)
(i) Journey time = 23 hour (accept 40 min) (ii)v1712+362
175 (km h–1) Direction = 12°

That's the mark scheme but how do you get 107 and 39?

draw a diagram. The velocity should point roughly north west. One component acts agaisnt the wind and is equal and opposite. The other component acts as the net velocity and points in the same direction as s

You can now treat it as a triangle use pythagoras's theorem to find the other length(velocity supplied by the engines) and use trig to find the angle(use tan)
Original post by BigDreamer123
You've done a and c but how to do b?

You didn't ask me to do b.
you need to draw a right angled triangle with the hypotenuse as s and the smaller sides pointing west and south.
use trig to find the smaller sides(the components)
How? And what angles to use
Original post by BigDreamer123
How? And what angles to use

For b:
WIN_20141218_231338.JPG112.2KB
For c:
WIN_20141218_232100.JPG116.0KB
Can you not make the triangle going south then west?
Original post by BigDreamer123
Can you not make the triangle going south then west?

Yes, it's just a rotation of the triangle going west then south. The components are the same.
Ok thanks a lot really helped

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