| Date | May 2021 | Marks available | 3 | Reference code | 21M.2.HL:.tz0.2 |
| Level | Higher Level | Paper | Paper 2 | Time zone | time zone 0 |
| Command term | Discuss | Question number | 2 | Adapted from | N/A |
Question
The diagram shows the forces acting on a high jumper.
State the forces labelled A, B, C.
A:
B:
C:
Outline friction.
Using sporting examples, discuss how an athlete can increase and decrease frictional forces to enhance their performance.
Markscheme
A: air resistance ✔
B: <body> weight ✔
C: ground reaction force ✔
friction occurs when two surfaces are in contact and inhibits the movement of one surface over another ✔
increase:
increase friction on the ground, so they can change directions more easily e.g. a football player uses studs/cleats ✔
increase friction on a surfboard and this helps them to apply push forces effectively on the board and so manoeuvre the board in the surf ✔
use of gloves to increase friction between hands and equipment e.g. gloves in baseball / golf ✔
increase the temperature of tyres in F1✔
decrease:
make the surface of equipment smoother to reduce friction e.g. a skier / luge runner puts wax on the bottom of the ski / luge so that it reduces the friction on the snow and speeds up movement ✔
Award [2 max] for either increase or decrease.
Examiners report
Some candidates were able to identify the three forces; however, many struggled with ground reaction force, commonly giving friction as the response.
Generally answered well, although at times candidates were very vague.
As a 3-mark question this is one of the questions where candidates did not provide enough examples to gain the marks allocated. Many candidates provided one example to increase friction and one to decrease friction. The most common examples were studs/spikes/cleats and the use of wax on skis. There is confusion and some misconceptions regarding the width of skates and tyres; these need to be addressed by teachers.
