When a ruler falls vertically, 5$5$ different persons catch it with different reaction times. (g=9.8 ~m s⁻²$\mathrm{g}=9.8\mathrm{~m\ s^{-2}}$) A. Person A has reaction time of 0.20 ~s$0.20 \mathrm{~s}$. B. Person B has reaction time of 0.22 ~s$0.22 \mathrm{~s}$. C. Person C has reaction time of 0.18 ~s$0.18 \mathrm{~s}$. D. Person D has reaction time of 0.19 ~s$0.19 \mathrm{~s}$. E. Person E has reaction time of 0.21 ~s$0.21 \mathrm{~s}$. What is the correct order of the distance travelled by the ruler for each person?

Related Formula

v = u - gt$v = u - gt$

Slope of v$v$-t$t$ graph = a = -g$a = -g$

Core Logic

During the entire journey (thrown vertically upwards and falling back down), the ball is under the constant influence of gravity acting vertically downward.

Assuming the upward direction is positive, the acceleration is a = -g$a = -g$ (a constant negative value).

Since acceleration is the slope of the velocity-time (v-t$v-t$) curve, the graph must be a straight line with a constant negative slope throughout the whole flight.

Step 1: Identify Correct Graph

Looking at the options, only graph C

shows a straight continuous line starting with positive velocity, crossing zero at maximum height, and proceeding into negative velocity, maintaining a constant negative slope.

Pattern Recognition

For a free-falling body with no air resistance, the v-t$v-t$ graph is ALWAYS a single, unbroken straight line with negative slope (-g$-g$). Never a V-shape or curve.

Chapter Mix

Class 11 Physics: Motion in a Straight Line