Question

A body travels along a circular part of radius 70m. After travelling half a revolution in 20s find i) average velocity ii) average speed.​

Answer 1

Explanation:

Displacement = Diameter of circle

Diameter = 2r = 2×70 = 140 m

\begin{gathered} \implies \sf \: Average \: Velocity \: = \frac{Displacement}{Time} \\ \\ \\ \implies \sf \: \frac{140}{20} \\ \\ \\ \implies \sf \: 7m {s}^{ - 1} \end{gathered}

⟹AverageVelocity=

Time

Displacement

⟹

20

140

⟹7ms

−1

Average velocity = 7 m/s

Now ,

Distance covered by body = Circumference of Semi - circle

Circumference of semi circle = πr

We get,

↣ Distance = πr = 22/7 × 70

↣ 22 × 10

↣ 220 m

Now,

\begin{gathered}\implies\sf Average\:Speed\: = \dfrac{Total \: Distance \: Travelled}{Total \: Time \: Taken} \\ \\ \\ \implies\sf \: \dfrac{220}{20} \\ \\ \\ \implies\sf \: 11m {s}^{ - 1}\end{gathered}

⟹AverageSpeed=

TotalTimeTaken

TotalDistanceTravelled

⟹

20

220

⟹11ms

−1

Average speed = 11 m/s