# What torque would have to be applied to a rod with a length of #3 m# and a mass of #6 kg# to change its horizontal spin by a frequency #5 Hz# over #9 s#?

##### 1 Answer

Feb 9, 2017

#### Answer:

#### Explanation:

Assuming the rod in question rotates about the center (not the end), we know that

Step 1. Gather the information that you know and need

Mass of rod:

Length of rod:

Change in angular speed:

Change in time:

Torque required: ??

Step 2. Determine the formula using the above givens

Torque:

#I# is the moment of inertia of our rod- Assuming center spin,
#I_"rod"=1"/"12*m*L# #alpha# is the**instantaneous angular acceleration**#alpha=domega"/"dt# with units#"rad/"s^2# or#s^-2#

Torque:

Step 3. Plug your knows into the formula for torque