At an average of 80 km/h a motor car will cover 40km in

0.5 hours.

The radius of a circle is 7cm.Find it's diameter

The diameter of a circle is equal to twice the radius. Therefore, the diameter of a circle with a radius of 7 cm would be 2 * 7 cm = 14 cm.

To find the time it takes for a motor car to cover a distance at an average speed, we can use the formula:

Time = Distance / Speed

In this case, the distance is 40 km and the speed is 80 km/h. Plugging these values into the formula:

Time = 40 km / 80 km/h

To simplify, we can divide both the numerator and denominator by 40:

Time = 1 hour

Therefore, it will take 1 hour for the motor car to cover a distance of 40 km at an average speed of 80 km/h.

To determine the time it takes for a motor car to cover a certain distance, you can use the formula:

Time = Distance / Speed

In this case, the distance is 40 km and the speed is 80 km/h.

Substituting the values into the formula, we get:

Time = 40 km / 80 km/h

To simplify the calculation, we can cancel out the units of "km" in the numerator and denominator:

Time = 40 / 80 h

Simplifying further, we find:

Time = 0.5 h

Therefore, at an average speed of 80 km/h, a motor car will cover 40 km in 0.5 hours.