Lab 9: Rotation
By: Sydney Knight
The purpose of this lab was to experiment with why objects accelerate angularly using Newton’s Second
Law of Rotation. Also to explore the relationship between torque, angular acceleration, and moment of
inertia. A few technical terms you will see throughout the report will be torque, and angular acceleration,
moment of inertia. Torque is defined as a force that causes rotation. Angular acceleration is the rate of
change in angular velocity measures in radians per second. Lastly moment of inertia is when a rigid
object is freely rotating on a fixed axis and has a net torque acting on it when the object undergoes
angular acceleration. A summary of our findings state that in part one of the lab as time increased the
angular velocity did as well, no matter which driving pulley was used. However the larger the driving
pulley radius resulted in a higher torque, but overall all three driving pulley sizes had the same inertia.
The overall physics concept we used during this lab pertained to Newton’s Second Law of Rotation
which states that the angular acceleration is proportional to the net torque and inversely proportional to
the moment of inertia. Some equations that were useful during this lab ∆𝜔 were as follows:
𝑎𝑛𝑔𝑢𝑙𝑎𝑟 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 (𝛼) =
∆𝑡𝑖𝑚𝑒
𝑡𝑜𝑟𝑞𝑢𝑒 (𝒯) = 𝑟 ∗ 𝐹
𝑟
𝑚𝑜𝑚𝑒𝑛𝑡 𝑜𝑓 𝑖𝑛𝑡𝑒𝑟𝑖𝑎 (𝐼) =
𝛼
Angular Velocity vs Time
y = 0.4003x + 0.4849
8
7
6
5
Angular Velocity
4
3
2
1
0
-1 0 2 4 6 8 10 12 14 16 18
Time (sec)
1: Trial with the small driving pulley
By: Sydney Knight
The purpose of this lab was to experiment with why objects accelerate angularly using Newton’s Second
Law of Rotation. Also to explore the relationship between torque, angular acceleration, and moment of
inertia. A few technical terms you will see throughout the report will be torque, and angular acceleration,
moment of inertia. Torque is defined as a force that causes rotation. Angular acceleration is the rate of
change in angular velocity measures in radians per second. Lastly moment of inertia is when a rigid
object is freely rotating on a fixed axis and has a net torque acting on it when the object undergoes
angular acceleration. A summary of our findings state that in part one of the lab as time increased the
angular velocity did as well, no matter which driving pulley was used. However the larger the driving
pulley radius resulted in a higher torque, but overall all three driving pulley sizes had the same inertia.
The overall physics concept we used during this lab pertained to Newton’s Second Law of Rotation
which states that the angular acceleration is proportional to the net torque and inversely proportional to
the moment of inertia. Some equations that were useful during this lab ∆𝜔 were as follows:
𝑎𝑛𝑔𝑢𝑙𝑎𝑟 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 (𝛼) =
∆𝑡𝑖𝑚𝑒
𝑡𝑜𝑟𝑞𝑢𝑒 (𝒯) = 𝑟 ∗ 𝐹
𝑟
𝑚𝑜𝑚𝑒𝑛𝑡 𝑜𝑓 𝑖𝑛𝑡𝑒𝑟𝑖𝑎 (𝐼) =
𝛼
Angular Velocity vs Time
y = 0.4003x + 0.4849
8
7
6
5
Angular Velocity
4
3
2
1
0
-1 0 2 4 6 8 10 12 14 16 18
Time (sec)
1: Trial with the small driving pulley
