Question

The wheel of a cart is making 5 revolutions per second. If the diameter of the wheel is 84 cm, find its speed in km/hr. Give your answer, correct to the nearest km.

Answer 1

Given: The wheel makes 5 revolutions per second and its diameter is 84 cm.

Step-wise calculation:

1. Circumference = π × diameter

Taking π = `22/7`

Circumference = `22/7 xx 84` 

= 264 cm

2. Linear speed = Revolutions per second × Circumference

= 5 × 264

= 1320 cm/s

3. Convert to km/hr:

1320 cm/s = 13.2 m/s (since 100 cm = 1 m) and 13.2 m/s × 3.6 = 47.52 km/hr

4. Round to the nearest km:

47.52 ≈ 48 km/hr

The speed of the cart is approximately 48 km/hr.