gravity
no
Some have counter-weights (sash weights), some have latches that catch the window in certain positions, some have friction strips on the sides that try to hold the window wherever it's set.
When some materials are squashed,stretched,twisted or bent they exert force which acts in the opposite direction to the force acting on them.
Some weights feel heavier than others because of their mass and density. The more mass and density a weight has, the more force is required to lift it, making it feel heavier.
Centripetal force does not exist on its own as a standalone force, but rather it is a net force that acts towards the center of circular motion. Centripetal force is not a new or separate force but rather is provided by other forces in a system, such as tension, gravity, or friction. Centripetal force does not contribute to the speed of an object in circular motion, but rather acts to change the direction of motion.
You don't need to "do" weights, but most boxers do some strength training with weights!
Yes. A lot of boys do weights before girls. Some girls don't even do weights. A lot of girls do weights before boys as well. Some boys don't do weights either.
The function of a demonstration balance is to show the basic principles of mass and force as well as leverage. Some demonstration balance tools come with weights, but are a bit more expensive.
Yes, some work is converted into heat due to the friction.
If two 100N weights are attached to a spring scale, the scale will read a total force of 200N because the weights are acting downwards, pulling the scale downwards. The scale would give the same reading even if one of the weights were tied to the rope as it would still be exerting a downward force on the scale. Please note that the scale measures the total force acting on it, regardless of how the forces are distributed or connected.
The braided rope is better because it is made from nylon or polyester. It can hold heavier weights than a regular rope. It can stretch and some polyesters are waterproof.
The force used to overcome friction is the force of applied external pressure or kinetic energy. This force acts in the opposite direction to the frictional force, allowing objects to move past each other or slide across a surface with reduced resistance.