# Simple Torque Question

1. Apr 2, 2010

### putongren

There is no answer in the back of the textbook to the problem I did. I'm self-studying, so can someone check if my answer is correct.

1. The problem statement, all variables and given/known data
The forearm accelerates a 3.6 kg ball at 7.0 m/s2 by means of the triceps muscle. The forearm is 30 cm long and is perpendicular triceps muscle. Calculate the torque and the force exerted by triceps muscles.

2. Relevant equations

$$\tau$$ = I$$\alpha$$

$$\tau$$ = R x F

3. The attempt at a solution

a = 7.0 (m/s2), m = 3.6 (kg), r = .03 (m)
$$\tau$$ = I$$\alpha$$ , $$\alpha$$ = a/r, I = m*r2
= m*r2$$\alpha$$
= m*r*a
= 3.6*.03*7
$$\tau$$ = .756

$$\tau$$ = r * F
F = $$\tau$$/r
F = .756/.03
F = 25.2

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

2. Relevant equations

3. The attempt at a solution

2. Apr 3, 2010

### rock.freak667

Your answers are correct. Though you could have found the force (ma) first and then the torque (rF)