Question

A cr travells from Ato B with a speed of 30 km /hr and then reteurns to A with a speed of 50 km/hr .Find displacement of car and distance of car and also average speed of car

Answer 1

Answer:

Given:

Car travels from A to B with speed 30 km/hr and returns to A with speed 50 km/hr .

To find:

Displacement, distance and average speed of car.

Concept:

Distance is the total path length travelled by an object. Hence it is always greater than zero.

Displacement is the shortest length between the starting and ending point. Hence, it can be zero, negative or positive.

Average speed is the ratio of total distance to the total time .

Calculation:

Since starting and ending points are same , hence the displacement will be zero.

$\huge{ \red{ \sf{ \bold{displacement = 0 \: km}}}}$

Let the Length between A and B be s , So total distance be 2s.

$\huge{ \red{ \sf{ \bold{distance = 2s\: km}}}}$

Average speed has to be calculated as follows :

$avg. \: v = \dfrac{2s}{ \dfrac{s}{30} + \dfrac{s}{50} }$

$= > avg. \: v = \dfrac{2}{ \dfrac{5 + 3}{150} }$

$= > avg. \: v = \dfrac{2 \times 150}{8}$

$= > avg. \: v = \dfrac{150}{4}$

$= > avg. \: v = 37.5 \: km {hr}^{ - 1}$

So, final answer is :

$\huge{ \red{ \sf{ \bold{avg. \: v = 37.5 \: km {hr}^{ - 1} }}}}$

Answer 2

$\huge \underline {\underline{ \mathfrak{ \green{AnS}wEr \colon}}}$

Given :

• An object moves from A to B with speed of 30 km/h. (v1) = 30 km/h.

• And object also comes back to A with speed of 50 km/h (v2) = 50 km/h.

___________________________

To Find :

• Displacement
• Distance
• Average Velocity

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Solution :

As the object moves from A to B and then again comes to initial position that is A, Displacement will be 0.

Let, the distance from A to B be x .

So,

Distance = x + x = 2x

__________________________

And we have formula for average velocity :

$\large{\boxed{\sf{Avg_v \: = \: \dfrac{2v_1 v_2}{v_1 \: + \: v_2}}}} \\ \\ \implies {\sf{Avg_v \: = \: \dfrac{2 \: \times \: 30 \: \times \: 50}{30 \: + \: 50}}} \\ \\ \implies {\sf{Avg_v \: = \: \dfrac{2 \: \times \: 1500}{80}}} \\ \\ \implies {\sf{Avg_v \: = \: \dfrac{3000}{80}}} \\ \\ \implies {\sf{Avg_v \: = \: 37.5}} \\ \\ \underline{\sf{\therefore \: Average \: velocity \: is \: 37.5 \: ms^{-1}}}$