Archea is the correct answer. :) good luck!
Table 1: The horizontal pulling forces (F) and resulting acceleration (a) for the cart.
The cart experiences no motion when there is 0.1 N of horizontal force, so F=0 in this case. When one uses Newton's Second Law to find the acceleration caused by each force, it becomes clear that every row in the chart represents a horizontal force of approximately F=20 N. The best fit for the missing value is F=-30N.
Why people shouldn't be sent to Mars?
