Hello, there something that doesn't make sense to me in the attached problem, P16.3. You can see from the diagram that you will have two reculting reactions, R[SIZE="1"]A and R[SIZE="1"]B. According to what I know from statics, the reactions will be at the same angle theta as the incline of the...
Its not gravity because its not free falling. I can't believe I made that mistake. I would have to use Sum of forces=ma and find the acceleration if i wanted to use kinematics, right?
What I am thinking is similar to the following situation:
Lets say that I were on a train, sitting in my seat, at rest while the train too is at rest (lets say its at a stop). Then after a couple of minutes the train starts to move again, it moves east. I could get up from my seat and walk east...
When the cars start to move, yes the momentum is zero, they are moving in no direction at all. Let's say at time t=1s, they can all start moving in the same direction, we would have: (mv)[SIZE="1"]A+(mv)[SIZE="1"]B+(mv)[SIZE="1"]F=constant
That constant would just be a larger number than if I...
Here we are again...We have apully system as seen on page 1 of the attachment. I tried using the rectilinear motion equations, assuming a=constant, but the book's solution used the momentum-impulse equations and got a different answer.
I don't understand why my approach is incorrect... Thanks.
I have attached two very simple problems with their solutions. In the first problem the velocity of the mass center is not constant while in the second it is.
From my understanding, the mass center of a object that explodes continues to move as if the object had not exploded and if there are...
Doc Al, you said I know the flatcar is moving to the right from conservation of momentum...Initially I don't know any of the directions for the velocities. I assumed them and got an answer that was obviously wrong. So I know that my assumption is wrong. But how to I know from conservation of...
Yes I took left to be positive, why should the flatcar be negative? Its moving to the right? How do I know that? I assumed that car A, car B and the flatcar had a constant final velocities to the left, which made them all positive.
Attached is P14.2, a simple conservation of momentum problem with relative velocities. I have solved the problem on the second page. My answer is wrong because the signs of the velocities are wrong. I have no idea why. I am very bad at assuming directions and being consistent but I can't figure...
Ok, I solved the problem correctly, the signs make sense to me now. Going back to my original confusion as to why in P12.72 acceleration is not constant and in P12.126 it is. I've learned that in P12.126, acceleration is constant because the cables are all positioned at a constant angle, they...
I solved problem 12.72
I solved the problem and once again, I got the wrong answer because I have the wrong sign for the acceleration. I attached the problem and books solution as well as my solution.