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

Homework Help: Need Help with Newton's 1st and 2nd Laws

  1. Oct 3, 2006 #1
    Need Help with "Newton's 1st and 2nd Laws"

    In an inertial frame of reference, a series of experiments is conducted. In each experiment, two or three forces are applied to an object. The magnitudes of these forces are given. No other forces are acting on the object. In which cases may the object possibly move at a constant velocity of 256\;{\rm m/s}?

    The forces applied are as follows:

    1. 2 N; 2 N
    2. 200 N; 200 N
    3. 200 N; 201 N
    4. 2 N; 2 N; 4 N
    5. 2 N; 2 N; 2 N
    6. 2 N; 2 N; 3 N
    7. 2 N; 2 N; 5 N
    8. 200 N; 200 N; 5 N

    please help me out here.
  2. jcsd
  3. Oct 3, 2006 #2
    FBD FBD....sum up all the forces and equate to 0 since constant velocity
  4. Oct 3, 2006 #3
    FDB means options F, D, and B? thats it.i am not able to understand the question. can you please simplify so that i can understand and slove smiliar kind of questions in future.
  5. Oct 3, 2006 #4

    Doc Al

    User Avatar

    Staff: Mentor

    The thing to figure out in each case is whether it is possible for the forces to be oriented in such a way that they add to zero. (Here's an example: If two forces act on an object, one 10 N the other 100 N, can they possibly cancel each other? No.)
  6. Oct 3, 2006 #5
    FBD=free body diagram where u draw all the forces acting on the object.alrite suppose there is an upward force 100N and a downward force 200N and the object is moving at constant speed. so taking down as negative, it will be( summation force)100-200=m(0)..so there is a net force of 100N downward
  7. Oct 3, 2006 #6
    i really dont know how to do it..i would really appriciate if anyone can help me with the answer..
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook