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1. Kinematics-Review help

Ohhhhhh nvm! i just realized what you meant! 20/9.8= 2.0kg f=ma 10=2a therefore a= 5m/s^2 Thanks :D
2. Kinematics-Review help

Yea i just realized that thanks..so it would be 15+(-5) = 10 N But weight isn't only the mass, from what i know weight is equivalent to net force that's why it's measured in Newtons..that's where I'm getting confused! oh btw the answer at the back of the textbook says d) 5m/s^2
3. Kinematics-Review help

Hey guys, I reallly don't understand how to do this question. i'd really appreciate it if you can help me..thanks :) Homework Statement A person applies a force of 15 N [E] on an object of weight 20 N. If the force of friction has a magnitude of 5.0 N, what is the acceleration of the...
4. Optics - distance between object and image

sorry for the late reply but, thanks a lot for your help, I really appreciated it! :)
5. Optics - distance between object and image

so the equation is : 1/di +1/do =1/f 1/4do + 1/do = 1/20 Now I'm guessing we want to make do single... but i have to get rid of the 4 so since I'm dividing... 1/do^2 = 1/20 - 1/4
6. Optics - distance between object and image

umm.. di=4(do) but since we don't have do we can't solve for di
7. Optics - distance between object and image

Yes, I was thinking about that but how do I do it? Seeing as if i did m=di/do 4=di/do --but it leads me to a dead end or if i used 1/di+1/do=1/f i can only go as far as 1/di+1/do=1/20 then once again i get to a dead end!
8. Optics - distance between object and image

hello, Homework Statement A lens has a focal length of 20 cm and a magnification of 4. How far apart are the object and the image? Homework Equations m=di(image)/do(object) 1/di + 1/do = 1/f The Attempt at a Solution Well, I don't really know what to do, I feel like I don't have enough...
9. Newton's Law Problems

No i don't! But the modified version you gave me is right! I got 1.03! :) thank you soo much :cool:
10. Newton's Law Problems

so basically i would multiply mass with 9.81 m2 = 1(9.81) = 9.81 m1= 2(9.81) = 19.62 a= -19.62-(-9.81)sin20/3 a= 3.3m/s^2 (down) but the answer is supposed to be -1.03 m/s^2 (down)
11. Newton's Law Problems

Homework Statement A block of mass m1=2.0 kg on a frictionless inclined plane of angle 20 degrees is connected by a rope over a pulley to another block of mass m2=1.0kg. What are the magnitude and direction of the acceleration of the second block? Homework Equations...
12. Kinematics Problems

:frown:?

teheh, all the multiples of 9 are the same gifts
14. Kinematics Problems

so i basically cross-multiplied and got 35(x+50) = 40x which then gave me 35x + 1750 = 40x 1750= 40x-35x 1750=5x 350=x sub x=350 into x/35 350/35 = 10s That doesn't make sense because the final time is supposed to be 5:40 (basically 40 minutes to add onto 5:00)
15. Kinematics Problems

okay when i equated it i got 40t=x+50 and 35t=x now what do i do with the equations?
16. Kinematics Problems

sorry i made an error the question is at what time will you pass ms.jones on the highway? Does it change anything?
17. Kinematics Problems

Hello! I have another question ..sorry! Problem Mr. Jones lives 50 km away from you. You both leave home at 5:00 and drive toward the highway. Mr.Jones travels at 35km/h and you drive at 40km/h. At what time will you pass Mr.Jones? From the book the answer says: 5:40 This is what...
18. Kinematics Problems

^oh, thank you! :D
19. Kinematics Problems

^ Why did you make "d" negative? I also don't understand why you have two formulas :( and what I'm doing in each and what I'm trying to find in each!
20. Kinematics Problems

Homework Statement An object is dropped from a tower. If it had been thrown down at 60m/s, it would have taken half the time. What is the height of the tower? (acceleration is 10m/s^ down) Homework Equations d= v1(t)+1/2a(t)^ ----> I think you could use this a=v2-v1/t --> maybe...
21. Vector Problems

thank you! :) And to everyone else that helped! :)
22. Vector Problems

thanks, but i still don't understand what the question is asking me? What does it mean by "ground speed?"
23. Vector Problems

okay thanks. One more question.. well actually 2.. if someone knows how to solve problem 2 i would really appreciate knowing how! Average velocity is taken care of now but average speed you you subtract d2-d1 or add d1+d2? Same would go for time...
24. Vector Problems

By total displacement do you mean resultant displacement?
25. Vector Problems

Oh thanks, that makes more sense. So in the case of problem 1, I would take the resultant displacement- 6500m/ 92s (27 + 65) = 70.7 m/s [SW]
26. Vector Problems

So the average speed is going to be 2750 + 5810/ 27+ 65 which is 93m/s ?? The average velocity would be -2750 + (-5810) / 27+ 65 which is 93m/s (SW) Is it right that i added the signs for the velocity?
27. Vector Problems

But I thought that was for speed? I'm super confused! aghh... so what would be the answer now?

29. Vector Problems

Homework Statement A plane flies 2750 m[W] in 25s and then 5810m [S] in 67s a) What is the average speed of the plane? b) What is the average velocity of the plane? I tried doing it and I don't know if I'm right. My physics teacher can't explain anything for beans so could you please explain...