Question

Can someone help me with a formula or something.. im terrible at word problems.

Two forces with magnitudes of 25 and 30 pounds act on an object at angles of 10° and 100° respectively. Find the direction and magnitude of the resultant force. Round to two decimal places in all intermediate steps and in your final answer.

Answer 1

do you know how to add vectors?

Answer 2

v1: 25 cos(10 ) , 25sin(10 )
+v2: 30 cos(100) , 30sin(100)
--------------------------
r = add up the parts

Answer 3

i know how to do u*v but not that^^ lol

Answer 4

you know dot product but not addition .... i find that to be a bit odd :)

Answer 5

oh well, we just add up like parts is all, cos and cos ... sin with sin

the resultant vector is therefore:

x = 25cos(10)+30cos(100)
y = 25sin(10)+30sin(100)

the length is very pythagorean: sqrt(x^2+y^2)

and the direction is well, inverses .... and a little remembering signs if we know where things end up

Answer 6

i'm so sorry .. i still don't understand..
so i need to add x and y?

Answer 7

no, you need to find the vector that is defined as (x,y) this give us a way to determine the magnitude and direction of the results

Answer 8

we are given 2 vectors, we simply need to add up their like parts

v1 = (25cos(10),25sin(10))
v2 = (30cos(100),30sin(100))

the resulant r = (x,y) such that:

x = 25cos(10)+30cos(100)
y = 25sin(10)+30sin(100)

Answer 9

ohhhhhhhh.. that makes sence .. sorry.. late night homework is terrible.. so then after that what is the next step?

Answer 10

sense *

Answer 11

how do we measure the length of a vector? its very pythagorean ...

the length of r = sqrt(x^2+y^2) of course

Answer 12

remember to round to 2 decies as you work it, the instructions read so

Answer 13

now from trig:

tan(a) = y/x

therefore the inverse tan function gives us the angle

a = tan^(-1) (y/x) and that gives us the direction. just make sure to note if tangent needs to be positive of negative.

Answer 14

and to work out the problem i need to plug it all in to those formulas?

Answer 15

with any luck, yes. otherwise im remembering something totally beside the point :)

Answer 16

once we detemrine x and y, the rest is rather formulaic

Answer 17

Lol i think i'm close to giving up on this problem tbh .. it all looks like mumbo jumbo to me ... wanna help with another ?