FORCES AND SHAPE
4 marks · NormalA cyclist is riding along a straight, level road. The diagram shows the horizontal forces acting on the cyclist and bicycle:
Calculate the resultant force acting on the cyclist and bicycle.
State what happens to the motion of the cyclist as a result of this resultant force.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 8 N forwards N
(b) The cyclist and bicycle accelerate in the direction of the resultant force (forwards).
Common mistakes: Adding forces without considering direction
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · States or shows correct method (subtracts backward force from forward force)
A1 (a) · 1 mark · Correctly finds resultant force as 8 N (forwards) (follow-through)
B1 (b) · 1 mark · States motion changes (recognises object accelerates)
B2 (b) · 1 mark · Direction described as accelerating forwards/in the direction of the force
Worked solution
a) The forward force is 20 N and the backward (friction) force is 12 N. The resultant force is:
b) Since there is a resultant force in the direction the cyclist is moving, the cyclist and bicycle will accelerate forwards.