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

A stone is dropped from rest from a tower and reaches the ground in 4 s (g = 10 m s<sup>-2</sup>). The height of the tower is:

Answer: 80 m.

  • A 40 m
  • B 80 m
  • C 100 m
  • D 60 m

Correct answer: B. 80 m

Explanation: h = (1/2)gt<sup>2</sup> = (1/2)(10)(4<sup>2</sup>) = (1/2)(10)(16) = 80 m.

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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