First you need to make a difference between friction while object is stationary and the friction while object is moving. Force required to start moving some object is slightly greater than force required to maintain objects movement. That means that to move a chair you need some force F1 but you can than slightly reduce force and chair will still be moving.
Now to the problem in this question: It can be said that "stationary friction force" is equal to 15 Newtons. Its also good to know that friction force between chair and floor while you are increasing your push is also increasing and is equal to force of your push. Once it reaches 15N which is it "critical value" for that chair, chair starts moving and friction force drops a little bit and now it is called friction force of moving chair.
Answer:
Surface tension
Explanation:
When liquid rises against gravity in a capillary tube, the energy comes from surface tension.
This is because surface tension is the energy that's needed to increase the liquid surface area.
As a result of hydrogen bonding present in Water, it usually has high surface tension which makes it to possess a tough skin that can make it not to break despite high forces applied to it.
The liquid will be in contact with the capillary tube and as such experiences surface tension which in turn makes the capillary tube to experience an upward force that makes the liquid begin to rise up.
The more the liquid keeps rising, the more it gets to the point where the surface tension becomes balanced from the weight of the liquid.
Answer:
1 st question: Control variable
2nd question: random variable
3rd question: if the two objects are dropped from the same height they will hit the ground at the same time
I think its the last one, a student slips on the ice in front of school and sprains his ankle. An example of a natural fiber could be cotton B.
The answer to this question is going to be False
