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Pure maths vector help

soph1a

can someone help me figure out these questions

Reply 1

IWMTom

Original post by soph1a

can someone help me figure out these questions

There's so much wrong with this thread I don't even know where to begin...

1) this is the Cars and Motoring section
2) you haven't posted any questions

Moved to the Maths section, but it'd probably help if you did post the questions!

(edited 5 years ago)

Reply 2

soph1a

Question 1b.
Questions 2 and 3
Question 8 ii. (Particularly c)

This question

Original post by soph1a

can someone help me figure out these questions

we will try & help on the Maths forum. please post the questions.

Reply 5

soph1a

Okay hopefully this is the last time I make this thread Im just going to copy and paste the questions over

Reply 6

soph1a

Original post by the bear

we will try & help on the Maths forum. please post the questions.

Forces F1 and F2 act on a particle

F1 = -3i + 7j newtons
F2 = i-j Newtons
Resultant force R acting on the particle is given by R=F1+f2

a. Calculate magnitude of R in newtons (I get this bit)

b. Calculate the angle between the line of action of R and the vector j (don’t get this bit)

I’m self teaching myself maths from the book so I’m struggling with more problem based questions

Question 2:

For each of the following vectors, find

i. a unit vector in the same direction

ii. the angle the vector makes with i

c= -9i+40j (this is the vector)

Question 3:

Small boat S, drifting in the sea, is modelled as a particle moving in a straight line at constant speed. When first sighted at 09:00, S is at a point with position vector (-2i-4j(km relative to a fixed origin O, where i and j are unit vectors due east and due north respectively. At 9:40, S is at the point with position vector (4i-6j)km.

a. Calculate the bearing on which S is drifting

b. Find the speed of S

PS: Im getting a maths tutor after I’ve finished teaching myself Pure Maths 1 so I’m not looking for the answers to these questions, I’m looking for how to go about solving them. Thank you

Reply 7

the bear

Original post by soph1a

[ul]
[li]Forces F1 and F2 act on a particle[/li]
[/ul]
F1 = -3i + 7j newtons
F2 = i-j Newtons
Resultant force R acting on the particle is given by R=F1+f2

a. Calculate magnitude of R in newtons (I get this bit)

b. Calculate the angle between the line of action of R and the vector j (don’t get this bit)

Q1 so the j direction is North. they want the angle between R and the North direction.

Reply 8

the bear

Q2 to find a unit vector you divide the vector by its magnitude

for instance the vector 3i - 4j has magnitude 5, so the unit vector would be .6i - .8j

the angle between c and the i direction is the angle between c and the East

Reply 9

the bear

Q3 you need to find the vector connecting the original position to the new position:

for instance:

original = 12i + 3j

new = 8i + 6j

connecting vector = -4i + 3j

the distance traveled = magnitude of the connecting vector = 5

if this takes 1 hour and 15 minutes....

speed = distance/time = 5/1.25 = 4 km/hr