A man drives his car uniformly at 30 km/h for three hour After it he covered next 90 km distance with uniform speed of 45 km/hr. Find the average speed of car.

Answer

To find the average speed of the car, we need to follow these steps:

### Step 1: Calculate the distance covered in the first part of the journey.
The man drives his car at a speed of 30 km/h for 3 hours.
- Distance (s1) = Speed × Time
- s1 = 30 km/h × 3 h = 90 km

### Step 2: Calculate the time taken for the second part of the journey.
In the second part, he covers a distance of 90 km at a speed of 45 km/h.
- Time (t2) = Distance / Speed
- t2 = 90 km / 45 km/h = 2 h

### Step 3: Calculate the total distance covered.
The total distance covered (S) is the sum of the distances from both parts:
- Total Distance (S) = s1 + s2
- S = 90 km + 90 km = 180 km

### Step 4: Calculate the total time taken.
The total time taken (T) is the sum of the time from both parts:
- Total Time (T) = t1 + t2
- T = 3 h + 2 h = 5 h

### Step 5: Calculate the average speed.
Average speed (V_avg) is given by the formula:
- V_avg = Total Distance / Total Time
- V_avg = 180 km / 5 h = 36 km/h

### Step 6: Convert average speed to meters per second.
To convert km/h to m/s, we use the conversion factor (1 km/h = 5/18 m/s):
- V_avg (m/s) = 36 km/h × (5/18) = 10 m/s

### Final Answer:
The average speed of the car is **10 m/s**.

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