Answer:
Accuracy measures how close results are to the true or known value. Precision, on the other hand, measures how close results are to one another.
Orbital periods of stars in the Galaxy
Answer:
B 14.5 m/s to the east
Explanation:
We can solve this problem by using the law of conservation of momentum.
In fact, if the system is isolated, the total momentum of the system must be conserved.
Here the total momentum before the stuntman reaches the skateboard is:

where
M = 72.0 kg is the mass of the stuntman
v = 15.0 m/s is his initial velocity (to the east)
The total momentum after the stuntmen reaches the skateboard is:

where
m = 2.50 kg is the mass of the skateboard
v' is the final velocity of the stuntman and the skateboard
Since momentum must be conserved, we have

And solvign for v',

And since the sign is the same as v, the direction is the same (to the east).
Ohm's law states that: 
Explanation:
Ohm's law states that in a conductor, the potential difference across the conductor is directly proportional to the current flowing through it. Mathematically,

where
V is the potential difference
I is the current
The constant of proportionality is called resistance (R), and it gives a measure of "how much the conductor opposes" to the flow of current. Therefore Ohm's law can be rewritten as

where R is the resistance. By rewriting the equation as

we see that the larger the resistance, the lower the current in the conductor.
Learn more about Ohm's law:
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Answer:
η = 2.57%
Explanation:
Given:
Output power of the steam power plant, P(out) = 200 MW
Consumption of coal, m = 700 tons/h = (700 × 10³)/3600 kg/s= 194.44 kg/s
Heating capacity of the coal, Cv = 40000 kJ/kg
now,
Input power, P(in) = mCv
or
P(in) = 194.44 kg/s × 40000 = 7777.77 MW
thus,
efficiency, η = P(out)/P(in) = (200 MW) / (7777.77 MW) = 0.02571
or
η = 2.57%