The purpose of this lab is for students to experience with rotation about a point external to the object and investigate the conservation of angular momentum about that external point.
Apparatus:
First part, we are going to roll a ball off a small ramp and measuring the distance the ball traveled. With the distance traveled and the height ramp off the floor, we can solve for the velocity of the ball as it leaves the ramp.
Second part, we attached a hanging mass onto the rotational apparatus and found the angular acceleration of the spinning disk. After find the angular acceleration, we had to find the inertia of the system.
Last part, we attach the ramp to the rotational apparatus, as shown below. The ball catcher will be attached onto the aluminum disk and the ramp should be angled so that the ball will roll right into the ball catcher at a right angle. As the ball rolls down and into the ball catcher, the disk should start spinning and this causes rotational acceleration.
Explanation:
For the first part of the lab, we solved for velocity using the conservation of energy. The traveled a height of 0.146m before entering kinetic energy, which gives us a velocity of 1.69m/s.
Then we attached a hanging mass of .0247kg onto a pulley which was settled in between the aluminum disk and the ball stopper. After collecting data from the apparatus, the angular acceleration was about 5.6365rad/s2. To find the Inertia of the spinning ball catcher and disk, we used Newton's 2nd law, which needed the angular acceleration for. The moment of inertia came out to be 0.001065kg*m2.
The last part of the lab was to put everything together. With the apparatus set up, we released the ball, and the ball rolled into the ball catcher. The disk started to move due to the motion of the rolling ball. This situation was an inelastic collision, which we set up the equation to find the final angular velocity. The final angular velocity was 1.945rad/s, and the actual angular velocity was 1.775rad/s. The percent error was 8.5%.
Conclusion:
For the first part of this lab, we needed to find how fast the ball will travel when it leaves the ramp. The second part of the lab is to find the moment of inertia of the spinning ball catcher and disk. The last part is to find the angular velocity and compare it will the theoretical value. The percent error was 8.5%, which means this lab experiment is acceptable.
Theory for first part should have mgh = 1.2 m v^2 + i/2 I w^2
ReplyDeleteV comes from where the ball hits the ground.