Final answer:
To determine the contact area of each of the 8 wheels of a caravan, calculate the force per wheel based on the total mass and divide it by the pressure. The contact area per wheel is found to be 196.2 cm².
Step-by-step explanation:
To find the contact area between each of the 8 wheels of a caravan and the track, we use the relationship between pressure (P), force (F), and area (A): P = F/A. First, we convert the caravan's mass from tons to kilograms: 64 tons is equivalent to 64000 kg. We then calculate the force exerted by the caravan on the ground using the gravitational force equation F = m * g, where m is mass and g is the acceleration due to gravity (9.81 m/s2). Thus, F = 64000 kg * 9.81 m/s2 = 627840 N. Since we have 8 wheels, the force per wheel is 627840 N / 8 = 78480 N per wheel.
To find the contact area, we need to rearrange the pressure equation: A = F/P. With the pressure given as 400 MPa, we first convert it to Pa: 400 MPa = 400 x 106 Pa. Then calculate the area per wheel: A = 78480 N / 400 x 106 Pa = 1.962 x 10-4 m2 or 196.2 cm2. Therefore, the contact area per wheel is 196.2 cm2.