Physics help Dx

• Isharo1 wrote on 2010-11-27 01:28
  Really cant figure this out :T_T: (sucks at physics) so if anyone knows any help would be greatly appreciated
  
  Q: A projectile is fired at an angle of 53 degrees to the horizontal and a speed of 80 m/s. What is the vertical component of the projectile's initial velocity?
  
  I tried 80 sin(53) but didnt seem to work out :x
• Blassreiter wrote on 2010-11-27 03:14
  It's suppose to be Cos(53). Because the angle we're looking at is the angle that is between the adjacent and hypotenuse. Because we have to find the vertical, we have to find the adjacent first and to find the adjacent you have to do Cos Angle=Adjacent/Hypotenuse which is Cos 53=A/80. Cross multply to get A=Cos 53(80. m/s) and the adjacent velocity should be about 48.1m/s. Now do a^2+b^2=c^2 which the newly found velocity is one of the a or b variable, and the 80 is the c. So it becomes 2318+b^2=6400 then 6400-2318=b^2. Find the square root of 6400-2318(which is 4082) to find b, and the vertical component should be about 64. m/s
  
  

  [Image: http://i94.photobucket.com/albums/l115/gaara12_01/Untitled-2.png]
• JustNoOne wrote on 2010-11-27 03:50
  Well when I do 80sin53, that gives me 63.891 (rounded to the nearest thousandths). I do not know how 80sin53 does not work for you... maybe you placed your calculator in Grad or Radians mode? That could be a possible reason.
  
  Now you can do it Blassreiter's way, but there are more steps because you're finding the adjacent side length and using Pythagorean's Theorem and find the opposite side, either one is correct, but doing 80sin53 is more accurate in terms of the numbers in behind the decimal because you are not running the risk of rounding out the number since in Blassreiter's way, you will have to find the value of 80cos53, which will give you a number with alot of digits behind the decimal.
• Isharo1 wrote on 2010-11-27 04:49
  Ok thanks alot for the help :D @JustNoOne when I do 80sin53 I get about 31.6 so not sure :x
• JustNoOne wrote on 2010-11-27 04:56

  Quote from Isharo1;230088:

  Ok thanks alot for the help :D @JustNoOne when I do 80sin53 I get about 31.6 so not sure :x

  
  
  Your calculator is in radiant mode, cause when I do 80sin53 in radian mode on my calculator, I get 31.6 as an answer... so change it to degrees now XD
  
  In all honesty, radians is easy to understand, but I assume you're not in grade 12, so keep on using degrees =D
• Ampersand wrote on 2010-11-27 05:47
  Maybe the answer in the back of the book is wrong!
• Isharo1 wrote on 2010-11-28 21:01

  Quote from JustNoOne;230094:

  Your calculator is in radiant mode, cause when I do 80sin53 in radian mode on my calculator, I get 31.6 as an answer... so change it to degrees now XD
  
  In all honesty, radians is easy to understand, but I assume you're not in grade 12, so keep on using degrees =D

  
  I am in grade 12 o3o thanks for the clear up just assumed my calc was in degrees cause it usually is >_> guess someone changed it
• Taycat wrote on 2010-11-28 21:05
  You have known this cuz Geometry should have taught you sin, cos, and tan.....
• Isharo1 wrote on 2010-11-28 21:11

  Quote from Xiyamae;231375:

  You have known this cuz Geometry should have taught you sin, cos, and tan.....

  
  /Almost failed geometry
• mocharate wrote on 2010-11-28 22:37

  Quote from Xiyamae;231375:

  You have known this cuz Geometry should have taught you sin, cos, and tan.....

  
  Nobody in america learns geometry anymore ._. Don't ask why.
• Taycat wrote on 2010-11-29 16:28
  My school made me.
  
  hur hur Coel doesn't know geo.
• Kueh wrote on 2010-11-29 16:35
  Geometry was fun because I got to play with shapes.
  
  Now I have to think for a long time in order to find out things no one cares about.