The rotating parts of the right front wheel assembly of a racing car have a mass of 35 kg and are measured to be out of balance. This unbalance can be corrected by attaching a 150 g lead weight to the 375 mm diameter wheel rim. The tire has a diameter of 700 mm. The car springs have a sti ness of 50 N/mm and the tire can be considered to have a sti ness of 600 N/mm, if the tire de ection is small. If the balance correction is not made, as what speed will resonant vibration of the wheel assembly occur