Question 10
A force of 10 N towards the west and a force X towards the east are applied to an object resting on a table. If the object is pulled along towards the west with a resultant force of 5 N, what is the magnitude of X?
The right answer is the one marked above.
5 N. The forces oppose, so resultant = 10 N − X. That is 5 N = 10 N − X, giving X = 5 N.
15 N comes from 10 + 5, which treats the forces as acting the same way. And if X were 10 N the resultant would be zero and the object would not move at all.