Work: only the part of the force along the motion counts
"Work: only the part of the force along the motion counts" is a free, interactive Class 11 Physics simulation for NEET and JEE, built on the lesson "Work" in Work, Energy and Power. Drag the purple tip to change the force F and the blue tip to change the displacement d. The thick shaded bar along d is F cos θ, the only part of F that does work. W = F·d = Fd cos θ, with θ the angle between F and d. Below 90° the work is positive, at 90° it is zero, and above 90° it is negative. JEE Main asked 44 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Work in Work, Energy and Power. Change the values and watch what happens.
In JEE Main
42 shifts analysed
44 questions from Work, Energy and Power across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT § "Work"
- Work done by a constant force F during a displacement d is W = F·d = Fd cos θ. Only the component of force along the displacement does work.
- Work is a scalar; its SI unit is the joule, 1 J = 1 N m. Other units: 1 erg = 10⁻⁷ J, 1 eV = 1.6 × 10⁻¹⁹ J, 1 kWh = 3.6 × 10⁶ J.
- No work is done if the displacement is zero (pushing a rigid wall), if the force is zero (a body moving freely at constant velocity), or if force and displacement are perpendicular.
- Work can be negative: the force of friction on a sliding body and the gravitational force on a rising body both do negative work.
- Always name the force whose work is asked for: the work done by gravity, by friction and by the applied force on the same body are separate quantities.
- When several forces act, the net work is the sum of the work done by each, which also equals the work done by the net force.
Questions
3 answers
- What does the "Work: only the part of the force along the motion counts" simulation show?
- Drag the purple tip to change the force F and the blue tip to change the displacement d. The thick shaded bar along d is F cos θ, the only part of F that does work.
- Does JEE Main ask questions from Work, Energy and Power?
- Yes. JEE Main asked 44 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Work" in Work, Energy and Power (Class 11 Physics).
Embed this simulation
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