Question

3. A man travels half length of a straight road with a constant speed of 20
m/sec, and he travels the second half length of the road with a constant
speed of 60 m/sec, then calculate its average speed.​

Answer 1

Answer:

$\boxed{\mathfrak{Average \ speed = 30 \ m/s}}$

Explanation:

Speed for first half distance ($\rm v_1$) = 20 m/s

Speed for second half distance ($\rm v_2$) = 60 m/s

Average speed is given as:

$\boxed{ \bold{v_{avg} = \dfrac{2v_1 v_2}{v_1 + v_2}}}$

By substituting values in the equation we get:

$\rm \implies v_{avg} = \dfrac{2 \times 20 \times 60}{20 + 60} \\ \\ \rm \implies v_{avg} = \frac{2400}{80} \\ \\ \rm \implies v_{avg} = 30 \: m {s}^{ - 1}$

Answer 2

Given :-

• A man travels half length of a straight road with a constant speed of 20 m/s, and he travels the second half length of the road with a constant speed of 60 m/s.

To Calculate :-

• It's average speed

Solution :-

We have,

• Speed for first half distance$(\sf v_1)$ = 20 m/s
• Speed for second half distance$(\sf v_2)$ = 60 m/s

We know that,

$\boxed{\sf v_{avg} = \frac{2v_1 v_2}{v_1 + v_2}}$

Substitute the given values we get,

$:\implies\sf v_{avg} = \frac{2 \times 20 \times 60}{20 + 60}$

$:\implies\sf v_{avg} = \frac{\cancel{2400}}{\cancel{80}}$

$:\implies\sf v_{avg} = \underline{\boxed{\blue{\sf30\:ms^{- 1}}}}$