Coefficient of Friction Lab

Procedure: Choose 1 material and 1 surface from the given list. Measure the mass of the material. Attach Newton's scale to the material and drag it along on the surface. Record the force it takes to move along the surface. Calculate the coefficient of friction using the formula F(friction) = umg.

Data & Calculation:

Error Analysis: There should be error in this lab due to small mass of materials. Small mass will lead to small friction force, which is hard to determine. Also, there might be some error in recording the force.

P.S: I actually don't like what I did. I think the way I did the lab (especially the friction force) is totally wrong. In my opinion, the force that I had from the Newton's scale is actually the applied force. To figure out what the friction force is, I must know the velocity of the object. The friction force should be F(applied) - F(friction) = ma

Soda Bottle Pre-Lab

Hypothesis: The carbon dioxide rocket is performed based on the Newton's Third Law. As the vinegar and baking soda mix together when the bottle is rotated, the reaction takes place and carbon dioxide (CO2) is produced. Carbon dioxide will cause the cork flies forward. As the cork flies forward, it applies the equal force but opposite direction to the container, making the container flies in the opposite way.

Procedure: Pour 200 mL of fresh vinegar into a 2-liter plastic container. Place a rubber stopper in the mouth of the container and then position it on round pencils. Then use aluminum foil to make a trough. Fill the trough with baking soda and carefully insert it into the mouth of the bottle. When everything is set up completely, rotate the bottle. The baking soda and vinegar will mix together and produce carbon dioxide, which makes the stopper flies out of the mouth and cause the container flies backward.

• How much force is necessary to dislodge the stopper from the bottle?

Measure the mass of the stopper and the bottle (with vinegar). Record the time that the stopper moving. Measure the distance the stopper travels after being dislodged from the bottle. Calculate the acceleration the stopper using the motion equations. Find the force acting on the stopper using Newton's Second Law.

Washer/Elevator Lab

Washer Lab:

• Observation: As we pull the washers at constant velocity, its weight is equivalent to its resting weight. When the washers, however, accelerates upward, its weight is greater than its resting weight. When the washers accelerates downward, its weight is smaller than its resting weight

Question: 1) When the scale was decelerating, the value of a is negative; whereas when the scale was accelerating, the value of a is positive.
2) The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma.

Example: The toy car has a mass of 2kg. The car is accelerating with the acceleration of 2m/s^2. The applied force on the toy car is F = ma = (2kg)(2m/s^2) = 4 N.

3) If the air friction is negligible, a feather and a rock will hit the ground at the same time because free fall does not depend on the mass of an object.

4) As the force is held constant, mass of an object decreases will cause the acceleration increases because mass and acceleration have an inversely proportional relationship.

Elevator Lab:

Procedure: Record person's actual weight. Then record his weight as the elevator accelerates upward or downward.

Data: Person's mass: 179 lbs ~ 81.19 kg

Mass when elevator accelerates upward: 182 lbs ~ 82.55 kg

Mass when elevator accelerates downward: 176 lbs ~ 79.83 kg

Calculation: 

Upward: mg + ma = 82.55kg 

=> 81.19 ( -9.8 ms-2 + a) = 82.55

=> a = 10.82 ms-2

Downward: mg + ma = 79.83 kg

=> 81.19 ( 9.8 ms-s + a) = 79.83

=> a = -8.82 ms-2

Error Analysis: There will be slight errors in recording the person's weight.

Ballistic Pendulum 3

Post lab questions:

Initiative:

In my opinion, the kinematics experiment provides a more accurate data than the pendulum does. One possibility involves the distance being measured. In the kinematics experiment, a projectile is launched several meters from its source. The point of impact is then measured from the launch point. The pendulum experiment however involves measuring the difference in height of the center of mass of a pendulum. The heights measured are really small, and are only a fraction of that length. One additional possibility is in the pendulum experiments, as we tried 5 times, the ball always bounced off and did not completely attached to the pendulum bob. This will cause the error in the total mass after the collision, thus, lead to an error in the final velocity. 

Ballistic Pendulum 2

Observation: 

• Experiment 1: As the ball is fired from the gun, it will hit the pendulum bob and causes the pendulum bob rise a height h. By measuring the height h the pendulum bob rises, I can calculate the initial velocity of the ball before the collision.

• Experiment 2: As the ball is fired from the gun at height h on the table, it will travel in a projectile motion and land on a carbon paper placed on the floor. By measuring the distance that the ball travels horizontally, I can figure out the horizontal velocity of the ball.

Data: 

 Error Analysis:
The percent difference from 2 experiment is 15%. There must be, however, a possibility of human error. Perhaps we marked the wrong spot on a carbon paper during the experiment 2(lead to the wrong data in the distance the ball travels horizontally), or measured the angle inaccurately in experiment 1(lead to the wrong data in height). In addition, there will be a difference in initial velocity of these experiments because the launcher, in fact, did not launch the ball at the same velocity each time.

Ballistic Pendulum Lab 1

Procedure: 
    Part 1: Momentum and Kinetic Energy after the collision

• Measuring the masses of two bodies.
• Measuring the distance from the tabletop to the center of mass of the pendulum before collision (h1) and after collision (h2)
• Fire the steel ball (mass m) into the hollow pendulum.
• After the collision the pendulum will be brought to rest at its highest point by a set of ratchet teeth mounted on the base of instrument. Then, measure the distance, h, that the pendulum was raised (h = h2 - h1). Repeat this step 5 times and record all data. 
• Add the masses of the two bodies, then calculate the initial velocity of the projectile using the conservation of energy and conservation of momentum equations.

    Part 2: Momentum and Kinetic Energy before the collision

• Measuring the distance from the launch point to the edge of the paper (x1) and from the edge of the paper to the center of the shot distribution. (d)
• Fire the projectile across the room.
• Place a piece of carbon paper (carbon side up) on the landing spot and tape a white sheet of paper on top of the carbon.
• The ball will leave a mark when it lands. Determine the range of the projectile by measuring the location of the marks (x = x1 + d). Repeat 5 times and record all data.

Hypothesis: As after the collision, the pendulum will raise to h height. Kinetic energy will transform to potential energy. Total energy is always conserved. The momentum also is conserved.

Materials: The pendulum, launcher, carbon paper, measuring tape

Velocity and Acceleration Lab 2

Although there is a slightly different change in time, two Buggies are likely to travel with constant velocity. Blue Buggies takes little more time to reach the end. There were some unexpected errors during the: they slightly changed their direction while traveling, thus, causing a really really small acceleration. However, if the lab was performed perfectly, there would be no acceleration.
The velocity for Red Buggies is .51m/s; the velocity for Blue Buggies is .45m/s

Velocity and Acceleration Lab

Procedures: Mark every 1 meter on the floor with the measuring tape. Let 2 Dune Buggies (Red and Blue) run 7 meter total at the same time. Each time Buggies reach 1 meter, record the time. When have all of data, calculate the velocity the buggies travel during 1 meter, repeat the calculation 7 times for each buggy. Then, compare those values.

Observation: Based on the data from the lab, I think two Buggies travel with constant velocity.

 Data Table:

Vector Lab 2

When I was measuring the distance, I did it in feet. So I had to convert it to meter to meet the criteria. There must be some small error in data because I measured the long distance few times before adding them up. I think the hardest part is calculate the angle and direction of the displacement vector. Since the vector is in 3D, it is confusing to figure out the angle on the 3D graph.

1st and 2nd period:

3rd and 4th period:

5th period:

6th and 7th period:

Vector Lab

When I started this lab, I hadn't considered about 3-dimensional vector. I was surprised; it took me few minutes to choose the origin and determined the x,y,z axis. My initial thought was measuring x and y component, and then figure out displacement for each class. The material that I used to perform this lab was only a measuring tape. It was inconvenient to measure the long hallway with these measuring tape. 

Here is the data table.