# Homework Help: Force needed to accelerate electron

1. Jun 22, 2008

### MIA6

1. What force is needed to give an electron an acceleration of 1.00*10^10 meters per second2?
1) 9.11*10^-41 N 2) 9.11*10^-31 N 3) 9.11*10^-21 N 4) 1.10*10^43.
I used electron's mass times acceleration, but non of these is the answer.

2. Two concurrent forces of 6 newtons and 12 newtons could produce the same effect as a single force of _____
1) 5 N 2) 15 N 3) 20 N 4) 72 N
It just says the two concurrent forces, but I don't know the angle between them, then how can I find the resultant?

3. Two concurrent forces of 40 newtons and X newtons have a resultant of 100 newtons. Force X could be ____
1) 20 N 2) 40 N 3) 80 N 4) 150 N
It's like the same thing as the previous one, so how can I find it?

Thanks a lot.

2. Jun 22, 2008

### rock.freak667

Yes the answer is there, what did you use for mass of electron?

Consider if the two forces acted in the same direction,what would be the resultant. Then if they acted anti-parallel, what is the resultant?

You can eliminate two answers by thinking of how to get the maximum resultant force

3. Jun 23, 2008

### MIA6

Then, it's either 6 or 18, which non of them has the answer.

4. Jun 23, 2008

### rock.freak667

Right, so 6N is the min resultant force and 18N is the max. So if then if it acts at an angle it must lie between 6 and 18

5. Jun 24, 2008

### MIA6

Re: Force

Ok,I see. thanks.