How could you show that dissolving salt in water is a physical change?

By the simple process of evaporation we can show that salt in water is physical change because only the state of the matter has changed. Physical changes can often be reversed.

your picture is not part of the scientific method.

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )