If a strip of lightly cross-linked natural rubber initially at room temperature is heated in an oven, it can be observed to expand. If the same piece of rubber is stretched at room temperature to twice its original longitudinal dimensions then placed in the same oven, it can be observed to contract. How do you explain these phenomena

Find v(t), given acceleration a(t)=7j and initial velocity v(0)=k

What is a good example of instantaneous speed

Asmall electric heater, immersed in 80g of water in a calorimeter of 40j/k raises the temperature from 10.5 degree celsius to 25 degree celsius in 12 minutes. using the same apparatus with 50g of oil instead of water, it is found that the temperature of oil rises from 7 degree celsius to 27 degree celsius in 10 minutes. find specific heat capacity of the oil.