Work, Energy & Power Flashcards for NEET — 20 cards

First 8 of 20 Work, Energy & Power flashcards

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1. Card 1 of 20

   Define Work in terms of Force and Displacement.

   Hint: Work is a scalar quantity. SI Unit: Joule (J).

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   Answer

   W = F d cos(θ). Work is only done by the component of force along the displacement.

2. Card 2 of 20

   Under what three conditions is Work Done equal to zero?

   Hint: Centripetal force never does work!

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   Answer

   1. Displacement is zero (e.g., pushing a wall). 2. Force is zero. 3. Angle between Force and Displacement is 90° (cos 90° = 0) (e.g., tension in a pendulum).

3. Card 3 of 20

   How do you calculate Work done by a Variable Force?

   Hint: Area above the x-axis is positive work; area below is negative work.

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   Answer

   W = Area under F-x curve.

4. Card 4 of 20

   What is the relation between Kinetic Energy (K) and Linear Momentum (p)?

   Hint: If momentum is increased by x%, use this formula to find the % change in kinetic energy.

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   Answer

   K = p² / (2m) OR p = √(2mK).

5. Card 5 of 20

   Differentiate between Conservative and Non-conservative forces.

   Hint: Potential energy is ONLY defined for conservative forces.

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   Answer

   Conservative: Work done is independent of the path taken and zero in a closed loop (e.g., Gravity, Electrostatic, Spring force). Non-conservative: Work done depends on the path (e.g., Friction, Air drag, Viscous force).

6. Card 6 of 20

   What is the formula for the Potential Energy (U) stored in an ideal spring?

   Hint: The Work done by the spring force is W = -½ k x².

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   Answer

   U = ½ k x². The graph of U vs x is a parabola.

7. Card 7 of 20

   State the Law of Conservation of Mechanical Energy.

   Hint: If friction is present, use: W_friction = ΔMechanical_Energy.

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   Answer

   If only conservative forces are doing work on a system, the total mechanical energy (Kinetic + Potential) remains constant. K$_i$ + U$_i$ = K$_f$ + U$_f$.

8. Card 8 of 20

   How do you determine Stable Equilibrium from a Potential Energy (U) vs. Position (x) graph?

   Hint: Think of a ball resting at the bottom of a bowl.

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   Answer

   Stable: U is minimum. d²U/dx² > 0. Unstable: U is maximum. d²U/dx² < 0. Neutral: U is constant.