The average distance per unit time, when the body is moving with variable speed, is called average speed, Average speed \(=\frac{\text { Total distance travelled }}{\text { Total time taken }}\)

Answer: To find the average speed, follow the steps outlined in the solution: Step 1: Identify the total distance traveled and total time taken. The car travels 40 km in the first hour and 60 km in the second hour, so the total distance traveled is 40 km + 60 km = 100 km. The total time taken is 1 hour + 1 hour = 2 hours. Step 2: Substitute values into the average speed formula \(\text{Average speed} = \frac{\text{ Total distance travelled }}{\text{ Total time taken }} = \frac{100 \,\text{km}}{2\,\text{hours}}\) Step 3: Solve for average speed Divide the total distance (100 km) by the total time (2 hours) to find the average speed: \(\text{Average speed} = 50\,\text{km/h}\) Step 4: Determine the units The average speed will be in kilometers per hour (km/h) since distance is in kilometers and time is in hours. Therefore, the average speed is 50 km/h. Step 5: Interpret your result The car's average speed was 50 km/h over the two-hour period. This means that, on average, the car was moving at a speed of 50 km/h throughout its journey.