Tutor profile: Charlene E.
Subject: Basic Chemistry
Why does one need to apply hair conditioner on after shampooing?
Shampoo, like any other detergent, is a basic substance, with pH level higher than than 7. Detergents are generally used to break down grease so it can easily be washed off with water. However, detergents used for the body such as soaps and shampoos tend to dry out the skin and hair, so it is important to restore its natural pH level with the use of hair conditioner (for the hair and scalp) and lotion (for the skin).
Under room temperature, why does a metal spoon feel cold to touch compared to a wooden spoon?
Objects generally adapt the same temperature as its environment, which means in this case both spoons are warmer than our hands. However when we touch both spoons we may notice that the metal one feels colder than the wooden spoon, even though they have the same temperature. This is explained by their ability to conduct heat away from our hands. Metals are good conductors of heat, which means the metal spoon can easily take away the heat off our hand upon contact, so the hand feels cold. Wood, on the other hand, does not make the same effect since it is not a good conductor of heat.
Algebra word problem: In the year 2011, a mother was one more than eleven times as old as her daughter. In 2020, she was seven more than three times as old as her daughter. How old was her daughter in 2011? How about the mother's age in 2015?
Short answer: Daughter's age in 2011 is 3 years old. Mother's age in 2015 is 38 years old. Explanation: In solving word problems it's important to correctly translate the mathematical statement to equation, representing the unknown value as a variable. In the given problem, we will represent x as the daughter's age in 2011. Thus it follows that: 11x + 1 = mother's age (2011) x + 9 = daughter's age (2020) 3 (x + 9) + 7 = mother's age (2020) From here, we have to form an equation to solve for x. Think about this: the mother's age in 2020 is 9 more than her age in 2011. We can then express this as a mathematical equation below and solve for x: 11x + 1 + 9 = 3 (x + 9) + 7 11x + 10 = 3x + 27 + 7 11x - 3x = 27 + 7 - 10 8x = 24 x = 3 Thus, the daughter's age in 2011 is 3 years old. Let us cross-check our answer by solving the rest of the age values. 11x + 1 = 34 = mother's age (2011) 9 years later... x + 9 = 12 = daughter's age (2020) [correct, since it's 9 more than the daughter's age in 2011] 3 (x + 9) + 7 = 43 = mother's age (2020) [correct, since it's 9 more than the mom's age in 2011] Thus, the mother's age in 2015 is 38 years old, by adding 4 more years to her age in 2011.
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