Answer:
1 / f = 1 / o + 1 / i = (i + o) / o * 1
f = o * i / (o + i) = 60 * 30 / (60 + 30) = 1800 / 90 = 20 cm
Both the object and image are in positive space for a mirror
Answer:
The number of protons 6.19 more than electron.
Explanation:
Given that,
Charge 
We know that,
formula of charge

Where,
Q = total charge
n = number of protons
e = charge of electron
Put the value into the formula



According to statement of question
Divide the answer by 


Hence, The number of protons 6.19 more than electron.
Answer and explanation;
According to twin studies attitudes may be genetically based, research has supported that Identical twins are more likely to share similar attitudes. Attitudes change as the result of behavior and not the other way around
Genetic factors may influence general dispositions and condition-ability that may influence formation of more specific attitudes. Controlled twin studies in US and Sweden reveal that identical twins share more similar attitudes than fraternal twins.
Solar energy, because of solar panels, hydroelectricity from a dam, or fossil fuels. fossil fuels would be the most ideal because it is more commonly used
Answer:
work output is always less than work input - the ratio is less than 1.
Explanation:
This principle comes from the fact that a machine or system cannot produce more work than is supplied to it, because this would violate the energy conservation law (work is a type of mechanical energy).
In theoretical machines called "ideal machines" the input work is the same as the output work, but these machines are only theoretical because in real applications there is always some type of energy loss, either in heat produced by a machine or processes for its operation, for this reason the output work is always less than the input work.
Regarding the ratio work output to work input:

because work input WI is always greater than work output WO.