Which of these actions will increase friction? check all that apply.
scratching a surface to make it rougher
polishing a surface to make it smoother
increasing the size of a flying object
adding extra weight to an object
placing oil between two surfaces

scratching a surface to make it rougher

increasing the size of a flying object

adding extra weight to an object

Explanation:

Friction exists between two surfaces when they are or tend to be in relative motion. This happens due to the interlocking of the microscopic hills and valleys structure of the two surfaces. Friction depends on the roughness of the surface. If a surface is scratched, it can be made more rough and thus, friction would increase. Polishing or oiling the surfaces can reduce friction between them. Friction can also be increased by increasing the weight of the object. It is difficult to move a heavier body. also, with increase in the contact surface, friction increases. Therefore, if the size of a flying object is increased, air drag increases.

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this

find the sum of the two horizontal vectors and the sum of the two vertical vectors

isoceles right angled triangle