Question

an object travels with a speed of 20ms-¹ for 20s and 40ms-¹ for next 40s find average speed of the object
ans is (33.3-¹)​

Answer 1

Given :

➳ An object travels with a speed of 20m/s for 20s and 40m/s for 40s.

To Find :

⟶ Average speed of object.

SoluTion :

⇒ Average speed is defined as the ratio of total distance travelled to the total time taken.

⇒ It is a scalar quantity having only magnitude.

⇒ SI unit : m/s

$:\implies\sf\:v_{av}=\dfrac{d_1+d_2}{t_1+t_2}$

$:\implies\sf\:v_{av}=\dfrac{v_1t_1+v_2t_2}{t_1+t_2}$

$:\implies\sf\:v_{av}=\dfrac{(20)(20)+(40)(40)}{20+40}$

$:\implies\sf\:v_{av}=\dfrac{400+1600}{60}$

$:\implies\sf\:v_{av}=\dfrac{2000}{60}$

$:\implies\boxed{\bf{v_{av}=33.33\:ms^{-1}}}$

Answer 2

Given -

• Object travels with a speed of 20m/s For 20s & 40m/s For 40s

To Find -

• Average speed of the object

Solution -

We know, Formula For Calculating Average Speed -

$★ \frac{(V1T1 + V2T2)}{(T1 + T2)}$

Here,

• V denotes Velocity For first & second terms
• T denotes time For first & second terms

Placing Values,

$⟹</strong><strong>a</strong><strong>v</strong><strong> </strong><strong>=</strong><strong> \frac{(20)(20) + (40)(40)}{(20 + 40)}$

$⟹</strong><strong>a</strong><strong>v</strong><strong> </strong><strong>=</strong><strong> \frac{(400 + 1600)}{60}$

$⟹</strong><strong>a</strong><strong>v</strong><strong> </strong><strong>=</strong><strong>\frac{\cancel{2000}}{\cancel{60}}$

$⟹</strong><strong>a</strong><strong>v</strong><strong> </strong><strong>=</strong><strong>33.33 {ms}^{ - 1}$

⛬ Average speed of object is 33.33ms^-1