Chapters

## Exercise 1

A Roman emperor was born in 63 B.C. and died in 14 A.D. How many years did he live?

## Exercise 2

A bomb displaces the oil in a well from 975 m deep and raises it to a deposit place 48 m above ground level. How far does the oil displace?

## Exercise 3

What is the change in temperature a customer in a grocery store experiences when they walk from the chilled vegetable section at 4 ºC to the frozen fish section which is set to −18 ºC?

## Exercise 4

The air temperature in the atmosphere decreases at the rate of 9 ºC every 300 meters. What height would a plain have to fly to experience a temperature of −81 ºC? The temperature is 0º C at sea level.

## Exercise 5

In a well there is 800 liters of water. At the top there is a pipe that deposits 25 l per minute into the well, and at the bottom there is another pipe which withdraws 30 l per minute from the same well. How many liters of water will there be in the well after 15 minutes of the pipes functioning?

## Solution of exercise 1

A Roman emperor was born in 63 B.C. and died in 14 A.D. How many years did he live?

14 − (−63) = 14 + 63 = 77 years

## Solution of exercise 2

A bomb displaces the oil in a well from 975 m deep and raises it to a deposit place 48 m above ground level. How far does the oil displace?

48 − (−975) = 48 + 975 = 1023 meters

## Solution of exercise 3

What is the change in temperature a customer in a grocery store experiences when they walk from the chilled vegetable section at 4 ºC to the frozen fish section which is set to −18 ºC?

−18 ºC − 4 ºC = −22 ºC

4 ºC − (−18 ºC) = −22 ºC = 4 ºC + 18 ºC = 22 ºC

The temperature difference in absolute value is equal in both cases. The minus sign of the first case tells us that it produces a drop in temperature, and the plus sign of the second case, an increase.

## Solution of exercise 4

The air temperature in the atmosphere decreases at the rate of 9 ºC every 300 meters. What height would a plain have to fly to experience a temperature of −81 ºC? The temperature is 0º C at sea level.

|−81| : 9 = 81 : 9 = 9

300 · 9 = 2,700 m

## Solution of exercise 5

In a well there is 800 liters of water. At the top there is a pipe that deposits 25 l per minute into the well, and at the bottom there is another pipe which withdraws 30 l per minute from the same well. How many liters of water will there be in the well after 15 minutes of the pipes functioning?

800 + 25 · 15 − (30 · 15) =

800 + 375 − 450 = 1175 − 450 = 725 l

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