# Homework Help: Newton's laws

1. Aug 11, 2009

### bumblebeeliz

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

A force F applied to a mass m1 produces an acceleration of 3.0 m/s2. The same
force applied to a second object of mass m2 produces an acceleration of 1.0
m/s2.

a. Find the value of the ratio m1 / m2.
b. If m1and m2 are combined, what will be the acceleration of the combined mass (m1+ m2) under the action of the force F?

2. Relevant equations

F=ma

3. The attempt at a solution

a)

I didn't know where to begin. So I chose a random number and assumed that my force was 6 N.

6N = m1 a1
6N = m1 (3.0 m/s2)
6N / 3.0 m/s2 = m1
2 kg = m1

6N = m2 a2
6N = m1 (1.0 m/s2)
6N / 1.0 m/s2 = m2
6 kg = m2

m1/m2 = 2kg/6kg = 0.333 = 3 x 10 -1

b)

F = (m1+m2) a
6N = (2kg + 6kg) a
6N / 8kg = a
0.75 m/s2 = a

---

Any suggestions? :)

2. Aug 11, 2009

### rock.freak667

While this is correct. You didn't need to say F=6. It said the it applied the same force so F1=F2
or simply put m1a1=m2a2

So if F is the same, either F=m1a1 or F=m2a2

So you want F=(m1+m2)a . So you can put F equal to which either one you want and solve from there.

3. Aug 12, 2009

### bumblebeeliz

Makes more sense! Thanks :)