Question

The velocity-time plot is shown in figure. Find the average speed in time interval $t=0tot=40s$ during the period,

• A. $5m/s$
  
• B. zero
  
• C. none
  
• D. $2\cdot 5m/s$
  

Answer 1

The correct option is D $2\cdot 5m/s$


$\text{Avergae velocity}=\frac{\text{Total displacement}}{\text{total time}}$

Area under the curve above $x-$ axis ,
distance $\left(D_1\right)=\frac{1}{2}\times 20\times 5=50m$
Area under the curve below $x-$ axis,
distance $\left(D_2\right)=\frac{1}{2}\times 20\times 5=50m$

Then, total Distance $=100m$
Since, total time $=40sec$
Then, average speed is given by,

$\text{Avergae velocity}=\frac{\text{Total displacement}}{\text{total time}}$
$v_{avg}=\frac{100m}{40sec}$
$v_{avg}=2\cdot 5m/s$
Final Answer:$b$