Question

A man walks 450 m at an average speed of 3 m/s. How long is he walking for?​

Answer 1

Given:

Speed1 = 8 km/h

Time1 = 4 h

Speed2 = 12 km/h

Time2 = 4 h

Concept used:

If A travels with speed x km/h for t1 h and with speed y km/h for t2 h, then 

Average speed = (xt1 + yt2)/(t1 + t2)

1 km/h = (5/18) m/s

Calculation:

Here, x = 8 km/h, y = 12 km/h, t1 = 4 h, and t2 = 4 h

Average speed = (xt1 + yt2)/(t1 + t2)

⇒ Average speed = [(8 × 4) + (12 × 4)]/(4 + 4)

⇒ Average speed = 80/8 = 10 km/h

⇒ 10 × (5/18) m/s = (25/9) m/s

∴ The average speed of man is (25/9) m/s.

Answer 2

Answer:

Refer the attachment

Explanation:

Hope it helps you