1.
How many types of friction are there in total?
Correct Answer
D. 5
Explanation
There are five types of friction in total. Friction is the force that opposes the motion of an object. The five types of friction are static friction, sliding friction, rolling friction, fluid friction, and internal friction. Static friction occurs when an object is at rest and prevents it from moving. Sliding friction occurs when two surfaces slide against each other. Rolling friction occurs when an object rolls on a surface. Fluid friction occurs when an object moves through a fluid, such as air or water. Internal friction occurs within a material, such as the friction between molecules.
2.
What the nature of friction?
Correct Answer
C. It's a non-conservative force
Explanation
Friction is considered a non-conservative force because it dissipates energy and does not conserve mechanical energy. When two surfaces are in contact and in relative motion, friction opposes the motion and converts some of the kinetic energy into heat or other forms of energy. This means that the total mechanical energy of the system is not conserved in the presence of friction.
3.
What is dry friction?
Correct Answer
D. It's a force that opposes the relative lateral motion of 2 solid surfaces in contact
Explanation
Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. This type of friction occurs when there is no lubrication or fluid present between the surfaces. It is caused by the interlocking of microscopic irregularities on the surfaces, which creates resistance to sliding or motion. Dry friction is commonly experienced in everyday situations, such as when trying to push or slide objects across a rough surface.
4.
What is skin friction?
Correct Answer
A. It's a component of drag the force resisting the motion of a fluid across the surface of a body
Explanation
Skin friction is a component of drag that refers to the force resisting the motion of a fluid across the surface of a body. It occurs due to the interaction between the fluid molecules and the surface of the body, resulting in a frictional force that opposes the fluid's motion. This frictional force contributes to the overall drag experienced by the body as it moves through the fluid.
5.
What causes dry friction?
Correct Answer
C. A combination of inter-surface adhesion, surface roughness, surface deformation, and surface contamination
Explanation
Dry friction is caused by a combination of factors including inter-surface adhesion, surface roughness, surface deformation, and surface contamination. Inter-surface adhesion refers to the attractive forces between the surfaces in contact, which can contribute to friction. Surface roughness creates irregularities that increase the contact area and contribute to friction. Surface deformation occurs when the surfaces are compressed or distorted, leading to friction. Lastly, surface contamination, such as dust or oil, can also increase friction by interfering with the smoothness of the surfaces.
6.
What is mechanical energy?
Correct Answer
C. It's the sum of potential energy and kinetic energy
Explanation
Mechanical energy refers to the sum of potential energy and kinetic energy. Potential energy is the energy stored in an object due to its position or condition, while kinetic energy is the energy possessed by an object in motion. Therefore, the correct answer states that mechanical energy is the combination of both potential and kinetic energy.
7.
Who were the first ones to study friction?
Correct Answer
B. The Greeks
Explanation
The Greeks were the first ones to study friction. They made significant contributions to the understanding of friction through their observations and experiments. The Greek philosopher and scientist, Archimedes, conducted experiments on friction and developed the concept of static and kinetic friction. He also discovered that the force of friction is directly proportional to the weight of an object. The Greeks' studies on friction laid the foundation for further advancements in the field and greatly influenced the scientific understanding of this phenomenon.
8.
When were the classic laws of sliding discovered?
Correct Answer
D. In 1493
Explanation
In 1493, the classic laws of sliding were discovered.
9.
How many factors on friction did Coulomb Investigate?
Correct Answer
A. 4
Explanation
Coulomb investigated four factors on friction.
10.
When was the atomic force microscope created?
Correct Answer
A. In 1986
Explanation
The atomic force microscope was created in 1986.