dcf.cymru stimulus sheet · Science · Year 8

The Cwm Gwyn sponsored bike ride

The school, the path, every place name, every distance, every speed and the practice ride are invented for practice. The path is loosely based on old railway and riverside cycle paths in the south Wales valleys, such as the Taff Trail, but it is not a real route.

1: The plan

Year 8 at Ysgol Cwm Gwyn are riding 30 km along Llwybr Cwm Gwyn to raise money for the local mountain rescue team. Ms Pritchard, who is organising the ride, has split the route into 5 sections and estimated a steady speed for each one.

Section	From and to	What it is like	Distance (km)	Planned speed (km/h)
1	Parc yr Afon to Pont Haearn	Flat, smooth riverside path	6	15
2	Pont Haearn to Coed y Castell	Gentle climb through woods	4.5	9
3	Coed y Castell to Rhyd y Felin	Flat old railway line, rough gravel, open to the wind	9	12
4	Rhyd y Felin to Bwlch Garw	Steep climb	3	6
5	Bwlch Garw to Llyn Gwern	Long downhill. Group rule: no faster than 18 km/h.	7.5	18

The ride starts at 09:30 from Parc yr Afon.
The minibus leaves the finish at Llyn Gwern at 13:00. Everyone must be there by then.
There is a café at Rhyd y Felin, at the end of section 3. Ms Pritchard would like a 20 minute rest stop there.
Weather forecast for the day: a strong westerly wind. Ms Pritchard thinks riding into it on the open railway line (section 3) will halve the group's speed there.
The group rides together, so everyone goes at the speed of the slowest rider.

2: The practice ride

Last month, 4 riders rode sections 1 and 2 as a practice. One of them recorded the ride on a phone app, which drew this distance-time graph. They stopped once, at Pont Haearn, to fix a loose chain.

3: Elis's spreadsheet

Elis, in Year 8, built a spreadsheet of the plan. Here is what it shows. Some of it is wrong.

	A	B	C	D	E
1	Section	Distance (km)	Speed (km/h)	Time (h)	Time (min)
2	1	6	15	0.40	24
3	2	4.5	9	0.50	30
4	3	9	12	1.33	80
5	4	3	6	0.50	30
6	5	7.5	18	0.42	25
7	Total	30		3.15	164

Elis switched on “show formulas” and printed the formulas in columns D and E:

Row	Column D	Column E
2	=B2/C2	=D2*60
3	=B3/C3	=D3*60
4	=C4/B4	=D4*60
5	=B5/C5	=D5*60
6	=B6/C6	=D6*60
7	=SUM(D2:D6)	=SUM(E2:E5)