Some of these frictions depend on the Pressure, temperature of atmosphere.
Static Friction: This is the friction force when two objects in contact are not moving relative to each other. This friction is higher than kinetic friction.
Kinetic or Dynamic friction: this the friction force opposing the motion of objects, when two objects in contact are in motion relative to each other. It is less than the static friction. The two surfaces are rubbing against each other as they move.
Rolling friction: This is the friction when two objects are in contact and one object is rolling over the other - like a wheel on a road. The point of contact appears as stationary. The rolling friction is very less compared to static friction & dynamic friction.
Lubricated friction: this is the friction between two solid surfaces in contact with a layer of lubricant fluid flowing in between them. This friction is the least.
Fluid friction - viscosity : this is friction between two adjacent layers that are moving relative to each other at different speeds in a fluid. This is not high.
Internal friction: when an object is compressed and forced to deform, like in a piece of rubber, there is friction between the layers, that opposes this deformation.
Skin friction is the friction that opposes movement of a fluid across a solid surface. This is also called drag. When a coin is dropped in water, there is a friction called drag on the coin. Same is the case when a ball is thrown, a drag is experienced by the ball due to the drag of air.
the answer is c: kilogram
explanation: The standard International System of Units (SI) unit of mass is the kilogram (kg). The kilogram is 1000 grams (g), first defined in 1795 as one cubic decimeter of water at the melting point of ice.
If a football is kicked from the ground with a speed of 16.71 m/s at an angle of 49.21 degrees, then the vertical component of the initial velocity would be 12.65 m/s
<h3>What is Velocity?</h3>
The total displacement covered by any object per unit of time is known as velocity. It depends on the magnitude as well as the direction of the moving object. The unit of velocity is meter/second.
As given in the problem A football is kicked from the ground with a speed of 16.71 m/s at an angle of 49.21 degrees
The horizontal component of the velocity is given by
Vx = Vcosθ
The vertical component of the velocity is given by
Vy = Vsinθ
As we have to find the vertical component of the velocity given that speed of 16.71 m/s at an angle of 49.21 degrees from the ground
Vy = 16.71 × sin49.21°
Vy = 12.65 m/s
Thus, the vertical component of the velocity would be 12.65 m/s
Learn more about Velocity from here
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Answer:
1. the principle of original horizontality
2. the principle of crosscutting relationships
3. the law of superposition
4. older
5. younger
Answer:
When the volume increases or when the temperature decreases
Explanation:
The ideal gas equation states that:

where
p is the gas pressure
V is the volume
n is the number of moles of gas
R is the gas constant
T is the gas temperature
Assuming that we have a fixed amount of gas, so n is constant, we can rewrite the equation as

which means the following:
- Pressure is inversely proportional to the volume: this means that the pressure decreases when the volume increases
- Pressure is directly proportional to the temperature: this means that the pressure decreases when the temperature decreases