Speed：練習問題

A remote-control car moves at a steady speed of $$15$$ cm per second. How far does it travel in $$8$$ seconds?

A car travels a total distance of \( 450 \text{ km} \) at a constant speed. If the journey takes exactly \( 2.4 \text{ hours} \), how many minutes does it take for the car to travel this distance?

The table below shows the results of a \( 100 \text{-meter} \) sprint for four students. Student E runs at a constant speed of \( 7 \text{ m/s} \). Who is the fastest runner among all five students?

A child rides a scooter at a speed of $$5$$ km/h. How long will it take to ride $$25$$ km?

An elevator in a skyscraper travels from the \( 1^{\text{st}} \) floor to the \( 21^{\text{st}} \) floor in exactly \( 30 \text{ seconds} \). If the total distance covered is \( 60 \text{ metres} \), what is the speed of the elevator in \( \text{m/s} \)?

John cycles $$10 \text{ km}$$ in $$1$$ hour. Mary cycles $$10 \text{ km}$$ in $$30$$ minutes. Who cycles faster?

A truck travels \(180\text{ km}\) at an average speed of \(60\text{ km/h}\). A car starts at the same time as the truck and travels the same distance, but it arrives \(45\text{ minutes}\) earlier. What is the average speed of the car in \(km/h\)?

A cyclist travels from City A to City B. He covers the first \(40\%\) of the total distance at a constant speed of \(12 \text{ km/h}\). He then travels the next \(\frac{1}{3}\) of the total distance at a constant speed of \(15 \text{ km/h}\). Finally, he covers the remaining distance at a constant speed of \(20 \text{ km/h}\). If the entire journey takes exactly \(3\) hours and \(6\) minutes, what is the total distance between City A and City B in km?

A delivery van travels from a warehouse to a shop. The distance between the warehouse and the shop is \(15 \text{ km}\). The van travels at a constant speed of \(30 \text{ km/h}\).

(a) How many minutes does the journey take?

(b) If the van leaves the warehouse at 10:45 a.m., at what time will it arrive at the shop?

(c) On the return journey, the van takes \(45 \text{ minutes}\). What is the speed of the van on its return journey in \(\text{km/h}\)?

Two athletes, Ben and Chloe, are running a \(1500 \text{-metre}\) race. Ben runs at a constant speed of \(5 \text{ m/s}\). Chloe completes the first \(900 \text{ metres}\) in \(3 \text{ minutes}\) and the remaining \(600 \text{ metres}\) at a speed of \(4 \text{ m/s}\).

(a) How many minutes does Ben take to finish the race?

(b) What is Chloe's average speed for the entire race in \(m/s\)?

(c) Who wins the race, and by how many seconds?