Good in physics...anyone??*10 points*?

Question

someone help me solve these.i already answered #1 and 2...bUt i dont know how to soLve the rest.

q1=4 X 10^-6 C

q2=-3 X 10^-6 C

q3=-2.12 X 10^-6 C

q4=-2.12 X 10^-6 C

*10 cm apart from each other

angle=135

1. what is the magnitude of force exerted on charge q1 by charge q2?

ans: 10.8 N

2. what is the magnitude of force exerted on charge q1 by charge q3?

ans: 7.63 N

3. refer to question 2. what is the horizontal component of force exerted on q1 by q3?

a. 0 N

b. 0.108 N

c. 3.77 N

d. 5.39 N

e. 7.63 N

f. 10.8 N

4. what is the resultant force exerted on charge q1 by the other three charges?

5. if q1 were replaced by a charge of -4 X 10^-6 C, what would be the resultant force exerted on it by the other three charges?

(choose your answers from the choices given in question 3)

thanks sOo much! 10 points fOr best answer!;)

Answer 1

3: add factor with magnitude of cos(135): 0.7071

Answer: 7.63*0.7071 = 5.39

Note cos and sin correspond to the x-axis and y-axis...

I assume x-axis corresponds to "horizontal".

5: same magnitude different sign... should be e... then answer 2 should be -7.63 (minus 7.63)

4: use multiplication by cos and sin (using the appropriate individual angles between charges)  to find the individual horizontal and vertical component-forces then add for horizontal forces and do the same for the vertical components to arrive at the resultant horizontal and vertical forces...

Good luck.