Question

Ting Tong!

Question: Refer to the attachment.
_________...

(Physics)​

Answer 1

Explanation:

ANSWER:-

• 1st speed given as 30 km/h
• wnd speed given as 50 km/h.

So, we need displacement first.

What is Displacement?

• The shortest distance traveled by a body is Displacement.
• There are some necessary conditions also.
• If any object returns back at same position, then the displacement becomes zero.

Here, the object returns back to same position, hence displacement is zero.

To find distance, we have to take an assumption.

• Let us assume distance as "d".

So, as the distance value is unknown, taking the going and the coming path i.e

d+d = 2d is the total distance.

To find:- Average speed.

Now, we know that

$speed = \frac{distance}{time}$

Now, we know the speed and distance.

We need time to find the average.

$time = \dfrac{distance}{speed}$

Now,

$time = \dfrac{d}{30} hrs$

$time = \dfrac{d}{50} hrs$

Totalling them,

$\dfrac{d}{30} + \frac{d}{50}$

$= \dfrac{30d + 50d}{1500}$

$= \dfrac{8d}{150}$

is the total time.

Now, average speed,

$av.speed = \dfrac{ \frac{2d}{1} }{ \frac{8d}{150} }$

$= \dfrac{2d \times 150}{8d}$

$= 37.5 \: km/ \: hour$

Answer 2

Given-

Initial velocity, u = 30 km/h

Final velocity, v = 50 km/h

To find-

Displacement of car.

Distance travelled by car.

Average speed of car.

SoluTion-

(a) Displacement of the car will be zero, as the car returns to its initial position at last.

→ Displacement of car = 0 km

(b) Let distance travelled at first be x km and distance travelled at second be x km.

Total distance = 2x km.

We know that,

Speed = Distance/time

→ Time = Distance/speed

→ Time = x/30 h (in first case)

In second case,

→ Time = x/50 h

Total time = x/30 + x/50

→ Total time = (5x + 3x)/150

→ Total time = 8x/150

Average speed = Total distance/total time

→ Average speed = 2x/(8x/150)

→ Average speed = 37.5 km/h.

For finding distance the given information is insufficient.