JEE Main 2021 · 31 August · evening · Numerical answer · +4 / −0
A particle is moving with constant acceleration 'a'. Following graph shows v² versus x(displacement) plot. The acceleration of the particle is ___________ m/s².
Answer and solution
Answer 1
Solution
Physics sir · 3 steps
A straight line on a v² versus x graph means its slope is 2a, so read the slope and halve it.
- Pick the equation. For constant acceleration, v² = u² + 2ax. Plotting v² against x gives a straight line with intercept u² and slope 2a.
slope = (Δ (v²))/(Δ x) = 2a
- Read the slope. From point A (10, 40) to point C (30, 80): slope = (80 - 40)/(30 - 10) = 40/20 = 2 m s⁻². The intercept at x = 0 is 20, so u² = 20 m² s⁻², which fits the same line.
- So. 2a = 2, so a = 1 m s⁻².
The common slip: 2. Taking the slope itself as the acceleration gives 2, not 1. The slope of this graph is 2a.
The idea to keep. On a v² versus x graph, the slope is 2a and the intercept is u². Always halve the slope to get the acceleration.
Answer from the NTA final answer key. Solution by PrepWiser.