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⚛️ Physics  ·  Motion in a Straight Line  ·  NEET & JEE

A car travelling at 30 m/s is brought uniformly to rest over a distance of 75 m. The magnitude of its deceleration is:

Answer: 6 m/s 2.

  • A 4 m/s<sup>2</sup>
  • B 9 m/s<sup>2</sup>
  • C 6 m/s<sup>2</sup>
  • D 12 m/s<sup>2</sup>

Correct answer: C. 6 m/s<sup>2</sup>

Explanation: Using v<sup>2</sup> = u<sup>2</sup> &minus; 2as: 0 = 900 &minus; 2a &times; 75, so a = 900/150 = 6 m/s<sup>2</sup>.

tvuvTΔtΔvslope = aarea = displacement (s)

On a velocity-time graph for uniform acceleration, the slope of the line gives the acceleration and the shaded area under the line gives the displacement.

Concept context

Equations of motion, projectile motion, relative velocity. Foundation of all mechanics.

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