Final answer:
Yes, digging your feet into the sand on a hot beach can cool them off as the lower layers of sand are cooler than the surface heated by the sun.
Step-by-step explanation:
If you went for a walk on a hot beach, you could cool your feet off substantially by digging them into the sand. This is because the surface sand is heated by direct sunlight, while the sand below is cooler, having been insulated from the heat. When you dig your feet into the sand, they reach the cooler layers, thus feeling substantially cooler compared to the hot surface. This phenomenon is related to the specific heat of the sand, which is the amount of heat per unit mass required to raise the temperature by one degree Celsius.
The specific heat of sand is lower than that of water, meaning it will heat up and cool down faster than water does. Thus, when it's hot outside, the surface of the beach sand gets hot quickly, but just below the surface, the sand remains cooler.