A resultant force with a magnitude of 20 Newtons can be produced by two concurrent forces having magnitudes of:

Question

Choices:

1) 5 N and 10 N

2) 20 N and 20 N

3) 20 N and 50 N

4) 30 N and 5 N

Answer 1

Values of Forses must satisfy triangle inequality: a+b > c, a+c > b, b+ c > a.

1) 5 + 10 < 20 no

2) 20 + 20 > 20 OK!

3) 20 +20 < 50 NO

4) 20 + 5 < 30 NO

Only p[ossible case 2) 20, 20, 20

Answer 2

Keep in mind that the two forces will combine in accord with both magnitude and direction.

Suppose you are pulling something with a force of 20 N and someone else is pulling in the opposite direction with the same force. The net force is zero and nothing happens.

Look at each possible answer and try to find a way that the forces can combine to get a total of 20N.

1) 5 and 10: If these act in the same direction, the total is 15, and--if they add in opposite directions, the total is 5.

3) 20 and 50: In the same direction: 70, and in opposite directions: 30

Use the same thought process to evaluate choices 2) and 4)