Answer:
Coal
Explanation:
A fossil fuel is a fuel formed naturally over time from the remains of once-living organisms.
Sand and wind are not fossil fuels. Sand is formed when rocks and stones are finely ground down. Wind is the movement of air caused by different pressures.
Coal is a fossil fuel. It is formed when dead plant matter decays and then is exposed to high temperature and pressure over millions of years.
The coefficient of kinetic friction is ∪ = 3.699
What is Kinetic Energy?
The energy an object has as a result of motion is known as kinetic energy in physics. It is described as the effort required to move a mass-determined body from rest to the indicated velocity. The body holds onto the kinetic energy it acquired during its acceleration until its speed changes.
Given,
m = 50 kg
Force = 2.30 x 10^2 = 230N
Distance = 5.55m
Work done = 2.50 x 10^2 = 250 j
Using work energy principle:
F x d - ∪ x m x d = work done
230 x 5.55 - ∪ x 50 x 5.55 = 250
1276.5 - ∪ x 277.5 = 250
1276.5 - 250 = 277.5∪
1026.5 = 277.5 ∪
∪ = 1026.5 / 277.5
∪ = 3.699
Hence, the coefficient of kinetic friction is ∪ = 3.699
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True: a scientific fact is something that is absolute and unchanging.
a tendency of a body to do nothing or to remain unchanged.
To solve this problem, we will apply the concepts related to the linear deformation of a body given by the relationship between the load applied over a given length, acting by the corresponding area unit and the modulus of elasticity. The mathematical representation of this is given as:

Where,
P = Axial Load
l = Gage length
A = Cross-sectional Area
E = Modulus of Elasticity
Our values are given as,
l = 3.5m
D = 0.028m

E = 200GPa

Replacing we have,




Therefore the change in length is 1.93mm