Answer:
The velocity of the skateboard is 0.774 m/s.
Explanation:
Given that,
The spring constant of the spring, k = 3086 N/m
The spring is stretched 18 cm or 0.18 m
Mass of the student, m = 100 kg
Potential energy of the spring, 
To find,
The velocity of the car.
Solution,
It is a case of conservation of energy. The total energy of the system remains conserved. So,






v = 0.774 m/s
So, the velocity of the skateboard is 0.774 m/s.
Explanation:
Load (l) = 680N
Effort (E) = 500N
Length slope (l) = 12m
Height slope (h) = 8 m
Output = load * height
680 *8 = 5.44 *103 J
The Input = effort * length = 500 *12 = 6000J
the Mechanical advantage (M.A) = load effort= 600500=1.36
the Velocity ratio (V.R) =lh=128 = 1.5
the Efficiency =M.A100%V.R= 90.6%
Red shift of distant galaxies
Answer:
A theory changes based on new observations and testing.
Explanation:
A scientific theory is a product of multiple trials and repeated experiments. It usually follows after carefully conducting and testing the validity of the hypothesis.
A scientific theory provides an explanation into how something behaves.
A law just states a finding will not explain it.
Most theories are tenable and can be improved upon when new observations and testing are carried out.
Answer:
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