# Force, Acceleration, mass and time

1. May 24, 2012

### V0ODO0CH1LD

If I have a 1kg object moving on a straight path at 10m/s, I have to apply a force of 10N in the opposite direction to its trajectory to stop it completely, right? Does that mean I have to apply a force of 10N for one second to stop it completely? In that case, would a force of 10N for half a second only decelerate it to 5m/s and a force of 20N take half a second to stop it? And if that is the case wouldn't a wall have to apply a force much greater than 10m/s to stop the object, as it does, in fractions of a second?

2. May 24, 2012

### Staff: Mentor

Not necessarily. It all depends on how quickly you want to stop it.
If you do apply such a force for such a time, then you will stop it completely.
Exactly.
Yes.

3. May 24, 2012

### V0ODO0CH1LD

Thank you! That really helped!

4. May 25, 2012

### Lsos

Yes, the forces when hitting a wall can easily be orders of magnitude greater than "regular" forces, which is exactly why you don't want to run your car into a wall.

Last edited: May 25, 2012