Free-body diagrams, equilibrium & resolving forces
Practice Flashcards
Flip to reveal answersWhat is a free-body diagram?
Track your progress — Sign up free to save your progress and get smart review reminders based on spaced repetition.
All 12 Flashcards — Free-body diagrams, equilibrium & resolving forces
Sign up free to track progress and get spaced-repetition review schedules.
Question
What is a free-body diagram?
Answer
A sketch of **one object as a dot**, with an **arrow for every force acting ON it** (and nothing it pushes on other things).
Question
What does 'translational equilibrium' mean?
Answer
The **net (resultant) force is zero**, so the object stays at rest or moves at **constant velocity**.
Question
Is a force a vector or a scalar?
Answer
A **vector** — it has a size (in newtons) **and** a direction.
Question
Components of a force A at angle θ to the horizontal?
Answer
Horizontal $A_{H} = A\cos\theta$, vertical $A_{V} = A\sin\theta$. **Given** in the data booklet.
Question
'Resolve' a force — what does it mean?
Answer
Split it into a **horizontal** and a **vertical** part that together do the same job.
Question
Which is cos, which is sin (angle from the horizontal)?
Answer
**cos** = the side **next to** the angle (horizontal); **sin** = the side **opposite** it (vertical).
Question
What is tension?
Answer
A **pull along a rope or string**, acting on the object **away** from it along the rope.
Question
How do you apply equilibrium to a 2-D force problem?
Answer
Resolve every force, then set the total to **zero in each direction separately** (left = right, up = down).
Question
Why is the tension in a nearly-horizontal rope so large?
Answer
Only its **small vertical part** ($A\sin\theta$) holds the weight, so the **full tension** must be huge.
Question
Formula for weight?
Answer
$F_g = mg$ — mass × gravitational field strength (g = 9.8 N kg⁻¹). **Given** in the data booklet.
Question
Equilibrium vs at rest — same thing?
Answer
**No.** At rest is one case; moving at **constant velocity** is also equilibrium (net force still zero).
Question
A force makes 50° with the horizontal. Which component is bigger?
Answer
The **horizontal** ($A\cos 50°$) is slightly larger, since cos 50° > sin 50° — but check the angle's reference each time.
Read the notes
Full study notes for Free-body diagrams, equilibrium & resolving forces
Topic 1.2 hub
Forces and momentum
More from Topic 1.2
All flashcards in this topic
Physics exam skills
Paper structures & tips
Track your progress with spaced repetition
Sign up free — Aimnova tells you exactly which cards to review and when, so you remember everything before your IB exam.
Start Free