Question

For the displacement-time graph shown in figure, the ratio of the magnitudes of the velocities during the first two second and the next four second is

• A. 1 : 1
• B. 2 : 1
• C. 1 : 2
• D. 3 : 2

Answer 1

The correct option is B 2 : 1

Slope of displacement-time graph represents velocity.
Velocity from $t=0\text{sec}$ to $t=2\text{sec}$ is given by
$v_1=\frac{20}{2}{\text{ms}}^{-1}$
Velocity from $t=2\text{sec}$ to $t=6\text{sec}$ is given by
$v_2=-\frac{20}{4}{\text{ms}}^{-1}$ ($\because$ direction gets reversed)
$\Rightarrow$ Ratio of magnitudes of velocities $=\frac{v_1}{v_2}=\frac{10}{5}=2:1$