TENSILE STRESS AND ELONGATION DUE TO IMPACT LOAD – COURSE QUESTIONA car skidded off an icy road and became stuck in deep snow at the road shoulder. Another car, of 1600-kg mass, attempted to jerk the stuck vehicle back onto the road using a 6-m steel tow cable of stiffness k = 5000 N/mm. The traction available to the rescue car prevented it from exerting any significant force on the cable. With the aid of a push from bystanders, the rescue car was able to back against the stuck car and then go forward and reach a speed of 4km/h at the instant the cable became taut.
(a). If the cable is attached rigidly to the centre of mass of each car, estimate the maximum impact force that can be developed in the cable, and the resulting cable elongation.
(b). If in the above example, the mass of rescue car was 2800 kg, and steel tow cable of stiffness k = 2500 N/mm estimate the maximum impact force that can be developed in the cable, and the resulting cable elongation. Comment on difference in outcomes between case (a) and (b).