Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Force and angle

  1. Feb 13, 2009 #1
    1. The problem statement, all variables and given/known data
    how do we measure 2 forces on an angle?

    let's say we get an object that is moving ( a rocket?)

    the gravity pull it down while the rocket engineer gives more force.

    however to reach the highest height, we shot it at 90 degree(horizon). and also at that time, the gravity and engineer force are facing each other in a straight line.

    then what would happen if 2 forces are meet in different angles???

    such as 45 degree?

    2. Relevant equations
    I know the equations for forces, however what i am trying to understand is what is the effect of angle on forces?

    3. The attempt at a solution
    google get a bunch of useless inf...
  2. jcsd
  3. Feb 13, 2009 #2


    User Avatar
    Gold Member

    Forces are what are called vector quantities and need to be resolved into their respective components to analytically solve for the specific effect.
  4. Feb 14, 2009 #3
    do you know a good equation for it?
  5. Feb 14, 2009 #4
    You would draw a diagram representing the vector quantities, and solve for the resultant vector. Usually law of sine and cosine are helpful
  6. Feb 14, 2009 #5


    User Avatar
    Homework Helper

    Newton, I must tell you about an interesting demonstration I used to do for all my physics students. I had this light bulb hanging from the ceiling via an electromagnet. At the side of the room, at the same height as the bulb, I had a spring gun that could shoot a ball bearing toward the bulb. When the spring was released to shoot the bearing horizontally, the current to the electromagnet was cut so the bulb fell at the same time.

    The interesting thing was that the bulb and the ball fell the same way so the ball always hit the bulb! Even when I changed the stretch on the spring so it shot the ball faster or slower.

    It seems that the horizontal motion does not affect the vertical motion!

    When you shoot a rocket at an angle, you just figure out the horizontal and vertical parts of the motion separately, because one does not affect the other.

    PS I must confess that my gun did not shoot straight so the ball usually passed on one side or the other of the bulb. But the height was right!
  7. Feb 14, 2009 #6
    Newton V, good basic question. As you may have learned from your intro class, forces are represented by vectors. This is because they have magnitude (strength) and direction. What you should do
    1) draw a picture of the problem.
    2) Draw the force diagram,
    3) break the forces into components, in this case the horizontal and vertical directions,
    4) solve for your net force by adding the forces together in their component forms
    5) write your answer in component form using either vector notation or magnitude and angle form.

    ** You will need a to use some trig, but don't be afraid. They're just homework probelms.
  8. Feb 14, 2009 #7
  9. Feb 14, 2009 #8


    User Avatar
    Homework Helper

    Fall the same way - both ball and bulb are always at the same height. They have the same vertical motion.
  10. Feb 14, 2009 #9
    Do you have a video or some kind picture? i still don't get it... so they fall at the same spot? or they just meet at same height?
  11. Feb 14, 2009 #10


    User Avatar
    Homework Helper

    Sorry, no video. Imagine the bulb falling from the ceiling in the middle of the room. The ball is shot from the side of the room toward the bulb. They meet just above a garbage can so the glass from the bulb is neatly disposed of.
  12. Feb 15, 2009 #11
    oh i get it now, i thought you mean the ball hit the bulb before it fall...
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook