# Homework Help: Perpendicular Forces, Acceleration and Mass Problem

1. Feb 1, 2007

### rwishka

1. The problem statement, all variables and given/known data

Two perpendicular forces, one of 45.0 N directed upward and the second of 60.0 N directed to the right, act simultaneously on an object with a mass of 35.0 kg. What is the magnitude of the resultant acceleration of the object?

A. 8.68 m/s^2
B. 3.00 m/s^2
C. 5.25 m/s^2
D. 1.41 m/s^2

2. Relevant equations

F = ma to a = F/m

3. The attempt at a solution

a = F/35.0 kg

I simply don't understand what to do with the two forces? Should I draw a diagram? Please help me!

2. Feb 1, 2007

### cristo

Staff Emeritus
The acceleration on the particle will be due to the resultant force. How can you calculate the resultant of the two forces? Draw a diagram-- it may help you.

3. Feb 1, 2007

### rwishka

Would I use the Pythagorean Theorem?

I did (45.0)^2 + (60.0)^2 = c^2
c = 87.46 N

I plugged that into a = 87.46 N/35.0 kg, and got an incorrect answer.

What did I do wrong?

4. Feb 1, 2007

### cristo

Staff Emeritus
Your calculation for c is wrong. Try checking it again.

5. Feb 1, 2007

### rwishka

Sorry, c is 75 Newtons.

a = 75 N/35.0 kg
a = 2.14 m/s^2

Am I missing a step?

(Thanks for helping me so far)

6. Feb 1, 2007

### cristo

Staff Emeritus
Well, that's the answer I get. Either we're both overlooking something, or there's a typo in the question (I'd say that the latter was more likely!) Are you sure you wrote down the question and answers correctly (is there a possibility that the mass is 25kg?)

7. Feb 1, 2007

### rwishka

I checked and that is the problem. Hmm. Well, thank you for helping me! :)