Question

A car moves with the spped of 60 km/hr for 30 min. and 90 km/hr for next 40 min. What is the average speed of the car?

​

Answer 1

Answer is here ok thank t

Answer 2

Speed of the car = 60 km/h

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: 60 \times \frac{5}{18}$

$speed = 30 \times \frac{5}{9}$

$speed = 10 \times \frac{5}{3}$

$speed= \frac{50}{9} \: m \: </p><p>/\: s$

$t {}^{1} = 30 \: min = 30 \times 60 = 1800 \: seconds$

Distance (1) = speed × time

= 50 / 9 × 1800

= 50 × 200

= 10,000 m

Speed 2 of the car = 90 km/h

$= 90 \times \frac{5}{18} \\ \\ = 5 \times 5 = 25 \: m</p><p>/s$

$t {}^{2} = 40 \: minutes \\ = 40 \times 60 = 2400 \: seconds$

Distance (2) = speed × time

= 25 × 2400

= 60,000 m

Total Distance = distance (1) + distance (2)

= 10,000 + 60,000

d = 70,000 m

Total Time = t (1) + t (2)

= 1800 + 2400

t = 4200 seconds

Avg. Speed = d / t

$= \frac{70000}{4200}$

$= \: \frac{100}{6} \\ \\ = \: \frac{50 }{3} m</p><p>/s$

$= 16.66666.......... \: m</p><p>/s$

Avg. Speed = 16.67 m/s [approx.]