You take the same bend near Cauberg first at 30 km/h. If the centrifugal force there has the value 1, what value does the force have at 60 km/h in that same bend?
Show the answer
Correct answer: 4 x
Correct: 4.0 x.
Cornering: centrifugal force and reading the bend
What the exam asks here: Most students reason: twice the speed, so twice the force.
The trap
Many learners think: If you take a bend at twice the speed, the centrifugal force also becomes twice as large.
The rule is: The same bend at 30 km/h and at 60 km/h gives four times as much centrifugal force at 60 km/h, not twice
Challenge
Most students reason: twice the speed, so twice the force. The CBR exam designer knows you reason that way — and counts on exactly that. The book gives a quadratic relationship, not a linear one.
The model
Take the same bend once at 30 km/h and once at 60 km/h, and the centrifugal force at 60 km/h is four times as large (Book p.68) — not twice. That force always pushes you towards the outside of the bend.
Core
Centrifugal force pushes you towards the outside of the bend; it becomes stronger as the radius of the bend gets smaller and as your speed gets higher (Book p.68). The relationship with speed is quadratic: double the speed, and the force quadruples. Danger in a bend increases with three things at once: if the bend is sharp, when several bends follow each other closely, and when sight through the bend is obstructed, for example by trees. A warning sign often alerts you to such a bend beforehand — but watch out: some bends curve increasingly sharply inward, so your first assessment on entry can become outdated (Book p.67). Safely through a bend: assess the course of the bend in good time, choose the right gear and adapt your speed, judge the carriageway width, the state of the road surface and the camber, stay alert to oncoming traffic but also to slow vehicles ahead, and take account of your vehicle's handling characteristics, for example if you are heavily loaded (Book p.68). That camber works both ways: with positive camber the outer bend lies higher than the inner bend — that helps you hold the bend. With negative camber the risk of flying off the bend is greater (Book p.68).
Why it matters
On the road from Vijlen to Eys bends follow each other quickly, with trees blocking sight — exactly the combination the book warns about. Underestimate one bend that tightens more than expected, and the four-times-greater force at too high a speed pushes you straight into the verge.
Active recall
You take the same bend near Cauberg first at 30 km/h, then at 60 km/h. How does the centrifugal force at 60 km/h relate to that at 30 km/h?
Teach back
Explain: in which direction does centrifugal force push, how does it change with speed, and what is the difference between positive and negative camber?
Memory hook
Force = outside, quadratic: 2x speed = 4x force. Positive camber helps, negative camber = greater risk of flying off the bend.
The picture
Test yourself
On a windy Sunday afternoon you drive via Vijlen to Cauberg, a winding road in the South Limburg hills. In the same bend you drove 30 km/h last week, now you drive 60 km/h. How much greater is the force now pushing your car towards the outside of the bend?
Show the answer
Take the same bend once at 30 km/h and once at 60 km/h, and the centrifugal force at 60 km/h is four times as large (Book p.68) — not twice. That force always pushes you towards the outside of the bend.
Exam questions on this topic
At a car park in Vijlen a passenger says: 'Centrifugal force pushes you towards the inside of a bend, not the outside.' Is that correct?
- True
- False
Show the answer
Correct answer: False
Why learners get this wrong: Centrifugal force pushes your car towards the inside of the bend.
On a road near Wittem there is a bend with negative camber. What does that mean for your risk according to the book?
- The risk of flying off the bend is greater
- The outer bend lies higher than the inner bend, which is favourable
- It makes little practical difference to how you take the bend
Show the answer
Correct answer: The risk of flying off the bend is greater
False — outer bend higher than inner bend is precisely the feature of POSITIVE camber, not negative
Why learners get this wrong: With negative camber the outside of the bend lies higher than the inside, which is favourable.
Which factors make a bend more dangerous according to the book? (multiple answers possible)
- Sight through the bend is obstructed, for example by trees
- The bend is clearly marked with a warning sign
- Several bends follow each other closely
- The bend is sharp
Show the answer
Correct answer: Sight through the bend is obstructed, for example by trees; Several bends follow each other closely; The bend is sharp
False — a warning sign warns you before the danger, it is not itself a danger factor
Why learners get this wrong: A warning sign before a bend is itself one of the factors that make the bend more dangerous.
You enter a bend near Vijlen and judge the radius on entry. Halfway through, the bend turns out to tighten more sharply than expected. What is going on here according to the book?
- A bend radius is fixed on entry and does not change after that, this must be a different bend
- Some bends curve increasingly sharply inward; your first assessment can become outdated
Show the answer
Correct answer: Some bends curve increasingly sharply inward; your first assessment can become outdated
Why learners get this wrong: Once you have judged a bend on entry, the radius of the bend stays the same from then on — you do not need to adjust your assessment further.
Which points belong to 'driving safely through a bend' according to the book? (multiple answers possible)
- Accelerate as much as possible as soon as you see the bend coming
- Judge carriageway width, road surface and camber
- Choose the right gear and adapt speed
- Assess the course of the bend in good time
Show the answer
Correct answer: Judge carriageway width, road surface and camber; Choose the right gear and adapt speed; Assess the course of the bend in good time
False — the book advises adapting speed to the bend, not accelerating as much as possible beforehand
Why learners get this wrong: Driving safely through a bend means accelerating as much as possible as soon as you see the bend coming.
You take the same bend near Cauberg first at 30 km/h, then at 60 km/h. How does the centrifugal force at 60 km/h relate to that at 30 km/h?
- Twice as large
- Four times as large
Show the answer
Correct answer: Four times as large
At 60 km/h the centrifugal force is four times as large as at 30 km/h, not twice
Why learners get this wrong: If you take a bend at twice the speed, the centrifugal force also becomes twice as large.
The same bend at 30 km/h and at 60 km/h gives four times as much centrifugal force at 60 km/h, not twice.
- False
- True
Show the answer
Correct answer: True
The same bend at 30 km/h and at 60 km/h gives four times as much centrifugal force at 60 km/h, not twice
Why learners get this wrong: If you take a bend at twice the speed, the centrifugal force also becomes twice as large.
About Cornering: centrifugal force and reading the bend: which statement is correct?
- Once you have judged a bend on entry, the radius of the bend stays the same from then on — you do not need to adjust your assessment further.
- This force pushes you towards the OUTSIDE of the bend, and is stronger with a smaller bend radius and a higher speed.
- Whether a bend has positive or negative camber makes little practical difference to how you should take the bend.
- If you take a bend at twice the speed, the centrifugal force also becomes twice as large.
Show the answer
Correct answer: This force pushes you towards the OUTSIDE of the bend, and is stronger with a smaller bend radius and a higher speed.
This force pushes you towards the OUTSIDE of the bend, and is stronger with a smaller bend radius and a higher speed
Why learners get this wrong: Once you have judged a bend on entry, the radius of the bend stays the same from then on — you do not need to adjust your assessment further.
About Cornering: centrifugal force and reading the bend: which statement is WRONG?
- The same bend at 30 km/h and at 60 km/h gives four times as much centrifugal force at 60 km/h, not twice.
- Watch out: some bends curve increasingly sharply inward, so your first assessment on entry can become outdated.
- With positive camber the outer bend lies higher than the inner bend; with negative camber the risk of flying off the bend is greater.
- Centrifugal force pushes your car towards the inside of the bend.
Show the answer
Correct answer: Centrifugal force pushes your car towards the inside of the bend.
This force pushes you towards the OUTSIDE of the bend, and is stronger with a smaller bend radius and a higher speed
Why learners get this wrong: If you take a bend at twice the speed, the centrifugal force also becomes twice as large.
All practice questions of this topic
Frequently asked questions
‘If you take a bend at twice the speed, the centrifugal force also becomes twice as large’ – is that true?
No. The same bend at 30 km/h and at 60 km/h gives four times as much centrifugal force at 60 km/h, not twice
‘Centrifugal force pushes your car towards the inside of the bend’ – is that true?
No. This force pushes you towards the OUTSIDE of the bend, and is stronger with a smaller bend radius and a higher speed
‘Whether a bend has positive or negative camber makes little practical difference to how you should take the bend’ – is that true?
No. With positive camber the outer bend lies higher than the inner bend; with negative camber the risk of flying off the bend is greater
‘Once you have judged a bend on entry, the radius of the bend stays the same from then on — you do not need to adjust your assessment further’ – is that true?
No. Watch out: some bends curve increasingly sharply inward, so your first assessment on entry can become outdated
‘With negative camber the outside of the bend lies higher than the inside, which is favourable’ – is that true?
No. Outer bend higher than inner bend is precisely the feature of POSITIVE camber, not negative