C5_Application of speed

C5 Application of speed

Multiple Select

What are the common units for speed?

• km/h

• km/s

• m/s

• cm/h

Multiple Select

What are the two factors affecting speed?

• Sumikko Gurashi

• Distance

• Weather

• Time

Draw

Please draw the correct "DST triangle".

1. What am I calculating?
   (S/D/T?)

2. What is the required unit?

   (km/h OR m/s)

3. Convert to the required units
   (4000m -> 4km;
   40 mins -> 40/60 h)

Steps for solving:

Poll

An elevator takes only 7.5 s to go up from the ground floor to a level 18 m high. How many metres per second is its elevating speed?

Step 1. What am I finding now?

• Speed

• Time

• Distance

Poll

An elevator takes only 7.5 s to go up from the ground floor to a level 18 m high. How many metres per second is its elevating speed?

Step 2. What is the required unit now?

• m/s

• km/h

• m/h

Poll

An elevator takes only 7.5 s to go up from the ground floor to a level 18 m high. How many metres per second is its elevating speed?

• 18 / 7.5

• 7.5 / 18

18 ÷ 7.5

​An elevator takes only 7.5 s to go up from the ground floor to a level 18 m high. How many metres per second is its elevating speed?

​= 2.4

Its elevating speed is 2.4 m/s.

Multiple Choice

Mr Shen drove for 45 min along a coastline on a motorcycle. The motorcycle travelled a distance of 41 500 m. What was its travelling speed in km/h?

Step 1. What am I finding now?

• Speed

• Time

• Distance

Multiple Choice

Mr Shen drove for 45 min along a coastline on a motorcycle. The motorcycle travelled a distance of 41 500 m. What was its travelling speed in km/h?

Step 2. What is the required unit now?

• m/s

• km/h

Poll

Mr Shen drove for 45 min along a coastline on a motorcycle. The motorcycle travelled a distance of 41 500 m. What was its travelling speed in km/h?

Is "41500 (m) ÷ 45 (min) " the correct number sentence?

• Yes

• No

Mr Shen drove for 45 min along a coastline on a motorcycle. The motorcycle travelled a distance of 41 500 m. What was its travelling speed in km/h?

​41 ½ ÷

Multiple Choice

Fred and Lucy both ran 140 m. Fred finished in 24 s, while Lucy was 4 s slower than Fred. What was Lucy’s running speed in metres per second?

• 140 / 24

• 140 / (24 - 4)

• 140 / (24 + 4)

• I don't know...

Fred and Lucy both ran 140 m. Fred finished in 24 s, while Lucy was 4 s slower than Fred. What was Lucy’s running speed in metres per second?

Multiple Select

How long did Mr Ho travel?

• 50 mins

• 40 mins

• 5/6 h

• 50 / 60 h

Mr Ho tried to take a photo of the rural landscape with a drone in the sky. The drone took off at 07 : 40 and returned to its original location at 08 : 30. It travelled km in total. What was its flying speed in km/h?

Fred is running at a speed of 5 m/s.

1. How long can he run in 1 s?

2. How long can he run in 2 s?

   How do you find the answer?

Multiple Choice

Lucy jogged for 40 s at a speed of 4 m/s on the jogging trail.
How many metres did she jog?

Step 1. What am I finding now?

• Distance

• Speed

• Time

Multiple Choice

Lucy jogged for 40 s at a speed of 4 m/s on the jogging trail.
How many metres did she jog?

Step 2. How to find distance?

• Distance =
  Speed / Time

• Distance =
  Speed x Time

• Distance =
  Time / Speed

Multiple Choice

A coach departed from a hotel at 11 : 35 a.m. and arrived at a tourist spot at 1 : 15 p.m. The speed of the coach was 48 km/h. What was the distance travelled in kilometres?

Step1. What is the duration of time?

• 1 hour and 30 minutes
• 2 hours and 5 minutes
• 1 hour and 20 minutes
• 1 hour and 40 minutes

Draw

A coach departed from a hotel at 11 : 35 a.m. and arrived at a tourist spot at 1 : 15 p.m. The speed of the coach was 48 km/h. What was the distance travelled in kilometres?

Travelling in 2 directions...

1. Same direction

2. Opposite direction

Multiple Choice

Lucy’s walking speed is 0.9 m/s while Fred’s walking speed is 1.2 m/s. They start walking in the same direction along a straight road starting from the same spot at the same time.

How far apart are they after 1s in m?

• 0.9 + 1.2 = 2.1 m

• 1.2 - 0.9 = 0.3 m

• I don't understand...:(

Open Ended

Lucy’s walking speed is 0.9 m/s while Fred’s walking speed is 1.2 m/s. They start walking in the same direction along a straight road starting from the same spot at the same time.

Will the difference in distance (0.3 m) in every second change? Why?

Lucy’s walking speed is 0.9 m/s while Fred’s walking speed is 1.2 m/s. They start walking in the same direction along a straight road starting from the same spot at the same time. How far apart are they after 30 s in m?

Multiple Choice

Two trains depart from the same station at the same time in opposite directions. Their speeds are 93 km/h and
102 km/h respectively.

Which one is the correct diagram?

Multiple Choice

Two trains depart from the same station at the same time in opposite directions. Their speeds are 93 km/h and
102 km/h respectively.

How far apart are they after 1 h in km?

• 102 + 93 = 195 km

• 102 - 93 = 9 km

Two trains depart from the same station at the same time in opposite directions. Their speeds are 93 km/h and 102 km/h respectively. How far apart are they after 2.2 h in km?

Travelling in 2 directions...

1. Same direction ( - )

2. Opposite direction ( + )