Question

In a complete circular motion, first half circle is covered with 6.The other half circle is covered in two equal times intervals at speed 4 and 2 respectively.The average speed during the circular motion is

• A. 2
• B. 3
• C. 4
• D. 5

Answer 1

The correct option is C 4

Let's consider, $x=$ total distance covered to complete the circle.

1st half distance is covered with speed $6m/s$ and the other half-circle is covered into two equal time intervals at $4m/s$ and $2m/s$.

The time taken to complete half-circle,

$t_1=\frac{x/2}{6}=\frac{x}{12}sec$. . . . . . .(1)

Now rest half $\left(\frac{x}{2}\right)m$ covered by $4m/s$ and $2m/s$ is equal to

$\frac{x}{2}=4t+2t=6t$

$t=\frac{x}{12}sec$.

The time taken to complete 2nd half

$t_2=2t=\frac{x}{6}sec$

Total time taken, $t_T=t_1+t_2$

$t_T=\frac{x}{12}+\frac{x}{6}=\frac{x}{4}sec$

The average speed, $v_{avg}=\frac{x}{x/4}=4m/s$

The correct option is C.

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