Five physics riddles about force, friction, and tension

[Marco Barghi]

i have 5 ridles my teacher posts and i was wonder if somebody could help me and put in some adivce/tips.

1. If we push a crate at constant velocity, how do we know how much friction acts on the crate compare to our pushing force?

2. Give an example of something moving when a net force of zero acts on it.

3. When you weigh yourself, are you actually reading the support force acting on you, or are you really reading your weight?

4. When only a pair of equal and opposite forces act on an object, what is the net force acting on it?

5. How much tension is there in a rope that holds a 20-N bag or apples at rest?

go nuts guys!

 

[Chi Meson]

1, 2, and 4 are the same.

Time for you to go nuts.

 

[billiards]

Hints: c.f.

1. Newton I
2. see above Q for perfectly fine example, why?
3. Newton III
4. Vectors

 

[dynamicsolo]

1, 2, and 4 are the same.

In fact, all of them except #3 are about the same idea. What is true about an object when the net force on it is zero?

As for #3, consider the forces that act on the scale platform when you stand on it.

As for getting your questions or puzzles answered around here, you're supposed to share your own thoughts first before anyone will give you more guidance...