## College Physics (4th Edition)

The braking torque would have to be applied for a time of $1.6~seconds$
The angular impulse is equal to the change in angular momentum. We can use the change in angular momentum to find the time that the torque should be applied: $\tau~t = \Delta L$ $t = \frac{L_f-L_0}{\tau}$ $t = \frac{0-6.40~kg~m^2/s}{-4.00~N \cdot m}$ $t = 1.6~s$ The braking torque would have to be applied for a time of $1.6~seconds$.