Usually folks figure sand at 100 pcf. There are 27 cubic feet in a cubic yard. So to continue the answer the previous poster made... Using the 100 pcf average weight for sand, and that there are 27 cubic feet in a yard, then 2 yards is equal to 54 cubic feet and at 100 pcf, the total weight is 5400 lbs, or 2.7 tons.
The walking distance measure denotes the distance that can be travelled by walking in a fixed amount of time. In Japan, the standard measure for walking distance is 80 meters for 1 minute of walking time. It is the standard used in real estate listings. For example, if a building is a 10 minute walk from a particular park or train station, it is 800 meters away.
A long distance walk will require many more. Your weight x distance = energy used walking. Time does not matter as much as distance. If you speed up to walking a mile in 13 minutes or less, you will be burning more calories per mile. But for most beginning walkers, it is best to increase the distance before working on speed. A simple rule of thumb is 100 calories per mile for a 180 pound person.