Ok I guess the reason why I do not know how to do this problem is because I can not draw the proper free-body diagram...
Three blocks on a frictionless horizontal surface are in contact with each other as shown in Fig. 4-5. A force F is applied to block 1 (mass m1). (a) Draw a free-body diagram for eeach block. Determine (b) the acceleration of the system (in terms of m1, m2, m3), (c) the net force on each block, and (d) the force of contact that each block exerts on its neighbor. (e) If m1 = m2 = m3 = 12.0 kg and F = 90 N, give numerical answers to (b), (c), and (d). Do your answers make sense intuitively?
Ok here's the free body diagram that i drew. The last one I drew was wrong... I guess...
|m1| this represents the block m1 same thing goes for m2 and m3
--- words ---> this is a force with the words being the name of the force
free body diagram of forces in the x axes
------ the Force F exerted by unknown object onto the first block ------> <-------- Reaction force exerted by block onto the unkown object that applied the force ------- | this is the first block with mass m1 | --- contact force exerted by the first block onto the second ----- > <------ the reaction force exerted by the second block onto the third ------ | this is the second block with mass m2 |-------contact force exerted by the second block onto the third--------> <------This is the reaction force exerted by the third block onto the second ------- |this is the third block with mass m3 |
Is this free body diagram correct????
I understand that mass and force don't add up that's because this is the free-body diagram of the situation not the mathamatical relationship. Is this free body diagram correct?
Ok I can find the acceleration and do part (b) ok
defintion of net force = m a
cancel out the mass for the acceleration
(defintion of net force = m a)m^-1 = a = m^-1 net force
this gave me
a = m^-1 net force
plug in mass for whole unit
a = m^-1 net force = (m1 + m2 + m3)^-1 net force
this is what I got
a = (m1 + m2 + m3)^-1 net force
ok part c
I have no idea how to do because I think my free body diagram is wrong can you please tell me how to fix my free body diagram that way I can make sense of the answers you have given me.
ok part d
I have no idea how to do because I think my free body diagram is wrong can you please tell me how to fix my free body diagram that way I can make sense of the answers you have given me.
part e
I believe I can do this once I have figured out how to do the rest of the problem and dosen't need to be explained to me
THANKS!
At the college bookstore, or Barnes Noble, you can find Schaum's Outline Series, College Physics, in which problems such as this are detailed in solution. I recommend it to you.
Now. If F (90N) is pushing on M1, which is pushing also M2 and M3, and the acceleraltion is then 90/(12+12+12), that gives the acceleration of the system as 2.50/s^2
Now, if m3 is accelerating at 2.50m/s^2, the force pushing it (F3) has to be ma or 12*2.50=30N.
Now if some force F2 is pushing m2 and m3, then it must be (12+12)2.50=60N
And as a check, the force pushing F1 accelerates all three blocks, F1=(3*12)2.5=90N
To check if your free-body diagram is correct, you need to consider all the forces acting on each block.
Here's how you can revise your free-body diagram:
For block 1 (m1):
- Draw an arrow representing the applied force F in the direction it is being applied.
- Draw another arrow pointing towards block 2 to represent the contact force between block 1 and block 2.
For block 2 (m2):
- Draw an arrow pointing towards block 1 to represent the contact force between block 1 and block 2.
- Draw another arrow pointing towards block 3 to represent the contact force between block 2 and block 3.
- Draw another arrow pointing to the left to represent the reaction force on block 2 due to the contact force from block 1.
- Draw another arrow pointing to the right to represent the reaction force on block 2 due to the contact force from block 3.
For block 3 (m3):
- Draw an arrow pointing to the left to represent the contact force between block 2 and block 3.
- Draw another arrow representing the reaction force on block 3 due to the contact force from block 2.
Make sure that the arrows representing the forces are of the appropriate lengths and directions according to the problem statement.
Now let's go back to part c and d:
c) The net force on each block can be determined by analyzing the free-body diagram. For example, for block 1, the net force is equal to the applied force F. For block 2, the net force is the sum of the forces acting on it, which include the contact force with block 1 and the contact force with block 3. Similarly, for block 3, the net force is the contact force with block 2. Remember that the net force on each block should be the same value since they are in contact and experiencing the same acceleration.
d) The force of contact that each block exerts on its neighbor can be determined by analyzing the free-body diagram as well. For example, the force of contact between block 1 and block 2 is the same as the contact force on block 1, and it is the opposite in direction. Similarly, the force of contact between block 2 and block 3 is the same as the contact force on block 2, and it is the opposite in direction. The reaction forces are simply equal and opposite to the forces of contact.
Once you have revised your free-body diagram, you can proceed with solving parts c and d. For part e, you can use the given values of mass (m1 = m2 = m3 = 12.0 kg) and applied force (F = 90 N) to calculate the numerical answers for parts b, c, and d, using the equations and concepts you have mentioned.