# Tutor profile: Evan S.

## Questions

### Subject: Physics (Electricity and Magnetism)

If a resistor element with a resistance value of 10 ohms has a current of 1 amp flowing through it, what is the voltage seen over the resistor element? Assume the resistor is rated to hold the given amount of current and power applied)

This problem can be solved by applying ohms law; Voltage = Current x Resistance. V = 1 A x 10 ohms V = 10 Volts The volatage over the resistor is 10 volts.

### Subject: Mechanical Engineering

A mechanical engineering is designing a see-saw and wants to strap a large object to one side (ie rock), so the see-saw can be used by an only child. The heavy material is limited to a 25 Newton rock. The goal in designing a see-saw is to balance the weight at equilibrium, so the simple machine will always work to be balanced. The average child weight is 50 Newton and it has already been determined that the child will be 5 Meters from the fulcrum. What is the distance the rock needs to be placed to balance the system?

This problem can be solved with the equation: Work = Force x Distance First, it may help to draw the system to visualize the work being done. Determine your positive a negative directions, (the systems can be drawn either direction, child on the right or left) for this example we will place the child on the left and choose the counterclockwise direction of rotation to be positive. Therefore the child will apply for positive work and the rock will apply for negative work. Set up the equation, and set work to zero or the system to equilibrium: W = 0 = +(50N x 5m) + - (25N x d_rock) 250N-m = 25N x d_rock d_rock = 10 m The anwser is 10 meters

### Subject: Statistics

A study is performed to determine the most popular number between 1-10 of people in the United States. A team of researchers finds a large group of individuals (Approx. 10,000) and records their favorite number. When the researchers analyze the data to find a standard deviation, which standard deviation should they use Sample or Population?

When the data is analyzed the researchers should apply the sample standard deviation because they are looking at a data set that represents the full population which is all individuals in the United States. This dataset does not contain data for all individuals in the US and data for this full population would be near impossible to obtain. Therefore the sample data can be used to determine trends that represent the full population.

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