# Two forces applied to object in space find the minimum and maximum acceleration

1. Feb 2, 2010

### mganey1

Two forces are applied to a 2 kg object floating out in space. One force has a magnitude of 20 N and the other has magnitude of 30 N. Which of the following represent the minimum and maximum of the possible acceleration that the object can have, depending on the relative directions of the two forces? (consider magnitudes only)
(a) 0.0 m/s2, 15 m/s2
(b) 0.0 m/s2, 10 m/s2
(c) 2.1 m/s2, 4.4 m/s2
(d) 5.0 m/s2, 25.0 m/s2
(e) 0.0 m/s2, 8.3 m/s2

and the correct answer is D

2. Feb 2, 2010

### cepheid

Staff Emeritus
Hi mganey1, welcome to PF!

Based on the answer choices given, I'm concluding that this is supposed to be treated as a 1D problem, i.e. forces can only point "to the right" or "to the left." The maximum possible acceleration occurs when both forces act in the same direction, and therefore augment each other (i.e. they both contribute in the same way). The minimum possible acceleration occurs when the two forces act on the object in opposite directions, therefore partly cancelling each other out (i.e. each contributing to the acceleration in the opposite way).

Does that help?

3. Feb 2, 2010

### rl.bhat

Hi mganey, welcome to PF.
When the two forces are acting in the same direction, the net force is maximum.
Similarly tell me, when the net force will be minimum?

4. Feb 2, 2010

### mganey1

thanks for the help! so does this mean that it is simply a matter of adding and subtracting vectors?

5. Feb 2, 2010

### cepheid

Staff Emeritus
Yeah, but since this is a 1D problem, you don't even necessarily need the full vector notation, and can just use positive and negative scalars to distinguish between "to the right" and "to the left" forces, so it reduces to adding together numbers in order to find the net force.