Now that I understand forces with two objects a little more, I am aware that I made the learning process a little more difficult than what it is, and in reality, it is much more simple. The trick is knowing if the objects are in constant velocity or in constant acceleration. By knowing which it is, you can determine which object is exerting a greater force. If the velocity is constant, you know that the blocks are exerting an equal force. This is because the force from the push for the 45 kg ball becomes the normal force for the 10 kg ball, making them have the same force. Although the push isn't directly going to the smaller ball, because the big ball has that force and it is touching the smaller ball a normal force going left is created for the smaller ball. Friction on the smaller ball and friction + normal force on the bigger ball pull back on the balls, preventing it from accelerating, which is why it has a constant velocity. Although the balls are going to the left, they have a constant velocity and have equal forces on them. If I were to draw a force diagram for each of the balls during the motion it would look like this:
This is a picture of me holding a balloon blowing away (this was the only picture I could find that had tension! Because balloons are filled with helium, it is very light, lighter than air, which is why it wants to float up. I tried challenging myself, and hopefully it's correct!) We know that there is tension going in the downward direction because the object is floating upward and it is attached to the string underneath it. Since air is heavier than the helium in the balloon, there is very little weight. The tension is what balances the weight so the object stays idle. Because the object is hanging by a string and not sitting on a surface (unlike the other picture), there is no normal. Lastly, there is another force, wind that is making the balloon blow in a certain direction. If I am correct, the diagram should look like this:
Now that I understand forces with two objects a little more, I am aware that I made the learning process a little more difficult than what it is, and in reality, it is much more simple. The trick is knowing if the objects are in constant velocity or in constant acceleration. By knowing which it is, you can determine which object is exerting a greater force. If the velocity is constant, you know that the blocks are exerting an equal force. This is because the force from the push for the 45 kg ball becomes the normal force for the 10 kg ball, making them have the same force. Although the push isn't directly going to the smaller ball, because the big ball has that force and it is touching the smaller ball a normal force going left is created for the smaller ball. Friction on the smaller ball and friction + normal force on the bigger ball pull back on the balls, preventing it from accelerating, which is why it has a constant velocity. Although the balls are going to the left, they have a constant velocity and have equal forces on them. If I were to draw a force diagram for each of the balls during the motion it would look like this: 
This is a picture of me holding a balloon blowing away (this was the only picture I could find that had tension! Because balloons are filled with helium, it is very light, lighter than air, which is why it wants to float up. I tried challenging myself, and hopefully it's correct!) We know that there is tension going in the downward direction because the object is floating upward and it is attached to the string underneath it. Since air is heavier than the helium in the balloon, there is very little weight. The tension is what balances the weight so the object stays idle. Because the object is hanging by a string and not sitting on a surface (unlike the other picture), there is no normal. Lastly, there is another force, wind that is making the balloon blow in a certain direction. If I am correct, the diagram should look like this:
Hmm....the balloon idea is interesting, but I might argue with you about that drawing!
ReplyDeleteI still think the balloon's weight should be drawn downward. Why? Because the weight represents the earth's gravitational pull on the balloon. Even though the balloon floats and it's very very very very (very) light, it still has weight!
Otherwise, (if the balloon didn't have weight going down) the balloon would continuously fly up and up into outer space! Why does it stay nearEarth? Because it has some gravitational pull downwards - just real small.
I see your point, and I agree. Helium is lighter than air, but it still has weight. Would it go into outer space if it could handle the pressure? I'm not sure, but thanks for reading my blog carefully. it means a lot :)
ReplyDeleteI was really confused before reading your post but after I had a clearer understanding of free-body-diagrams and forces in and out of equilibrium. I am not kidding thanks Sandra for writing such an insightful blog post!
ReplyDeleteoemgeeeee you're awesome! anytime....thanks!
ReplyDelete