find the work done by the gravity and normal on the particle during its displacement from top to ground.
2 answers:
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Answer:
static coefficient = 0,203 & kinetic coefficient = 0,14
Explanation:
There are two (2) conditions, when the desk is about to move and when the desk is moving. In the attachements you can see the two free body diagram for each condition.
In the first condition, there is no movement and the force is 12 N, in the image we can see the total forces are equal to 0 and by the definition of the friction force we can get the static friction coefficient.
In the second condition there is movement in the direction of the force which is equal to 8 N, again by the definition of the friction force we can get the kinetic friction coefficient. Since the desk is moving with constant velocity there is not acceleration.
Refer to the diagrams shown below.
The normal reaction of the road on the automobile is equal to the weight of the automobile (Newtons 3rd Law).
That is,
N = mg (g = 9.8 m/s²)
When the road surface is dry, the resisting frictional force at the wheel is
F₁ = μ₁N
where
μ₁ = the kinetic coefficient of friction.
The value of μ₁ is about 0.7 - 0.9 on a dry road.
When the road is wet, the resisting frictional force is
F = μ₂N
where
μ₂ = the kinetic coefficient of friction on a wet road.
The value of μ₂ is about 0.1 - 0.4 on a wet road.
Because μ₂ < μ₁, the automobile tends to slip on a wet road, especially if the tires are worn.
The normal reaction of the road on the automobile is equal to the weight of the automobile (Newtons 3rd Law).
That is,
N = mg (g = 9.8 m/s²)
When the road surface is dry, the resisting frictional force at the wheel is
F₁ = μ₁N
where
μ₁ = the kinetic coefficient of friction.
The value of μ₁ is about 0.7 - 0.9 on a dry road.
When the road is wet, the resisting frictional force is
F = μ₂N
where
μ₂ = the kinetic coefficient of friction on a wet road.
The value of μ₂ is about 0.1 - 0.4 on a wet road.
Because μ₂ < μ₁, the automobile tends to slip on a wet road, especially if the tires are worn.