Final answer:
To find the bus speed in km/h, calculate the wheel's circumference and multiply it by the number of revolutions per minute, then convert from meters per minute to km/h, resulting in a speed of 52.92 km/h.
Step-by-step explanation:
The diameter of a wheel of a bus is 90 cm, which makes 315 revolutions per minute. To determine the speed of the bus in kilometers per hour, we first calculate the circumference of the wheel using the formula C = πd, where C is the circumference and d is the diameter. With π approximated as 22/7 and the diameter given as 90 cm, the circumference C equals 90 cm * 22/7 = 280 cm or 2.8 meters.
Next, we find out the distance traveled in one minute by multiplying the number of revolutions per minute by the circumference. Hence, the bus travels 315 revolutions * 2.8 meters/revolution = 882 meters per minute. To convert this to kilometers per hour, we multiply by 60 minutes (1 hour) and divide by 1000 to get from meters to kilometers, resulting in a speed of ((882 * 60) / 1000) km/h = 52.92 km/h.