Question

3) 2 m/s
4) 4 m/s
2. A car travels the first half of a distance
between two places a speed of 30 km/hr
and the second half of the distance a
50 km/hr. The average speed of the car for
the whole journey is
1) 42.5 km/hr 2) 40.0 km/hr
3) 37.5 km/hr
4) 35.0 km/hr​

Answer 1

Answer:

Hope it will help you....

Explanation:

The correct option is a) 42.5 km/hr

Answer 2

Answer

Given :-

• Velocity in first half , $\sf v_1 = 30 km/hr$
• Velocity in second half , $\sf v_2 = 50 km/hr$

To find :-

• Average speed - $\sf v_{avg}$

Solution :-

When the distance travelled is same,

$\boxed{\sf v_{avg} = \frac{2v_1v_2}{v_1 + v_2}}$

• $\sf v_1 = 30 km/hr$
• $\sf v_2 = 50 km/hr$

Substituting the value in formula :-

$\sf v_{avg} = \frac{2v_1v_2}{v_1 + v_2}$

$\sf v_{avg} = \frac{2\times 30\times 50}{30 + 50}$

$\sf v_{avg} = \frac{300 \cancel 0}{8 \cancel 0}$

$\sf v_{avg} = \frac{300}{8}$

$\sf v_{avg} = 37.5 km/hr$

$\boxed{\mathrm\red{Average \:speed = 37.5 km/hr}}$