Distance

### 1.1. Knowledge to remember

**a) Problem 1**:

A car travels for 4 hours at a speed of 42.5 km/hr. Calculate the distance traveled by the car.

Solution:

The distance traveled by the car in 4 hours is:

42.5 × 4 = 170 (km)

Answer: 170km.

*Comment: *To calculate the distance traveled by the car, we take the distance traveled by the car in 1 hour or the speed of the car multiplied by the travel time.

To calculate the distance, multiply the speed by the time.

We have: s = v × t

**b) Problem 2:**

A cyclist travels at 12km/hr for 2 hours and 30 minutes. Calculate the distance traveled by the person.

Solution:

2 hours 30 minutes = 2.5 hours

The distance traveled by the person is:

12 × 2.5 = 30 (km)

Answer: 30km.

### 1.2. Solve textbook exercises page 141

**Lesson 1 Textbook page 141**

A canoe travels at a speed of 15.2 km/hr. Calculate the distance traveled by the canoe in 3 hours.

__Solution guide:__

The distance traveled by the canoe in 33 hours is:

15.2 × 3 = 45.6(km)

Answer: 45.6km

Lesson 2 Textbook page 141

A cyclist rides a bicycle for 15 minutes at 12.6 km/h. Calculate the distance traveled by the person.

__Solution guide:__

Exchange 15 minutes = 0.25 hours.

The distance traveled by the bicycle is:

12.6 × 0.25 = 3.15(km)

Answer: 3.15km

Lesson 3 Textbook page 141

A motorbike starts from A at 8:30 a.m. with a speed of 42 km/hr and arrives at B at 11 a.m. Calculate the length of the distance AB.

__Solution guide:__

The time taken by a motorbike to go from A to B is:

11 hours − 8 hours 20 minutes = 2 hours 40 minutes

Change: 2 hours 40 minutes = \(2\frac{{40}}{{60}}\) hours = \(2\frac{{2}}{{3}}\) hour= \(\frac{8}{3}\)hour.

The length of the distance AB is :

42 × \(\frac{8}{3}\) = 112 (km)

Answer: 112km.

### 1.3. Solve textbook exercises on pages 141, 142

**Lesson 1 Textbook page 141**

Calculate the length of the distance in kilometers and write in the blanks:

v | 32.5 km/h | 210m/min | 36 km/h |

t | 4 hours | 7 minutes | 40 minutes |

S |

__Solution guide:__

We have the following table:

v | 32.5 km/h | 210m/min | 36 km/h |

t | 4 hours | 7 minutes | 40 minutes |

S | 130 km | 1.47 km | 24 km |

Lesson 2 Textbook page 141

A car starts from A at 7:30 a.m. and arrives at B at 12:15 with a speed of 46 km/hr. Calculate the length of the distance AB.

__Solution guide:__

The travel time of the car is:

12 hours 15 minutes – 7 hours 30 minutes = 4 hours 45 minutes

Change 4 hours 45 minutes = 4.75 hours.

The length of the distance AB is:

46 × 4.75 = 218.5 (km)

Answer: 218.5 km.

Lesson 3 Textbook page 142

Honey bees can fly at a speed of 8km/h. Calculate the distance traveled by the honey bee in 15 minutes.

__Solution guide:__

Change: 15 minutes = 0.25 hours.

The distance traveled by the honey bee is:

8 x 0.25 = 2 (km)

Answer: 2km.

Lesson 4 Textbook page 142

Kangaroos can move (running and jumping) at a speed of 14m/s. Calculate the distance traveled by the kangaroo in 1 minute 15 seconds.

__Solution guide:__

Change: 1 minute 15 seconds = 75 seconds

The distance traveled by the kangaroo is:

14 x 75 = 1050 (m)

Answer: 1050m.

.

=====

## Leave a Reply