# Homework Help: Force Problem - How do i get the inclination?

1. Sep 15, 2015

### rose123456789

A 10.0 kg object is resting on a horizontal surface with coefficient of friction of 0.7. Determine the minimum force F that can move this object. At what inclination should force F be applied? Present your answer in nearest hundredths.

I don't know how where to start?, How do i get the inclination ? thanks for the help

Last edited: Sep 15, 2015
2. Sep 15, 2015

### SataSata

I'm pretty sure there's an equation for this and you already have half of the variables. A quick google search would show you the answer. Try searching for coefficient of friction and in this case it's probably static friction.

3. Sep 15, 2015

### rose123456789

ok thanks!!!!!

4. Sep 15, 2015

### haruspex

Does that mean you found the answer?
Really you should be figuring this out for yourself using free body diagrams and applying the force balance equations. You'll learn more that way than looking the answer up. Besides, it often happens that there is some subtle difference between the problem you are trying to solve and the one you find lying around on the net.

5. Sep 15, 2015

### rose123456789

oh no, i'm still figuring out the answer

6. Sep 15, 2015

### rose123456789

i'm still figuring out the answer

7. Sep 15, 2015

### haruspex

Ok. Have you drawn yourself a force diagram? What forces do you have, and in what directions do they act?

8. Sep 15, 2015

### rose123456789

i calculated that the normal force is 98N and the friction force is 68.6N . and i dont know what is next

9. Sep 15, 2015

### rohitjinnu16

just take angle as some 'x' and force as F and write the equations .u wil get as
Fcos x=0.7(w-F sinx)
solving this u wil get the eq. as 10 cos x+7 sin x should me max for the force to be minimum.
and solving x=34.99 degrees

10. Sep 15, 2015

### rose123456789

how did you get 10 cos x +7 sin x

11. Sep 15, 2015

### rose123456789

ohhh ok i got it now thanks

12. Sep 15, 2015

### rohitjinnu16

kk fn.

13. Sep 15, 2015

### rose123456789

hahahahaha thanks a lot

14. Sep 15, 2015

### rose123456789

ok i'm a bit lost could you explain how did you get 10 cos x +7 sin x

15. Sep 15, 2015

### rohitjinnu16

F cos x =0.7(w-F sin x)
F cos x/0.7=w-F sin x
F((cos x/0.7)+sin x)=w
F(10 cos x+7 sin x)/7=w
F=(7w)/(10 cos x+7 sinx)

16. Sep 15, 2015

### haruspex

You have not allowed for the applied force being at some angle to the horizontal. What will that do to the normal force?