+1 862 207 3288 Lab report covering 3 experiments conducted over Newton’s laws
Report should include an abstract, introduction, Methods and procedures, Results, and Discussion Section
Experiment 1: Newton’s First Law of Motion
In this experiment, you perform a series of motions and analyze the results to explain Newton’s First Law of Motion.
Materials
(1) 3″ by 5″ Notecard
(1) 8 oz. Styrofoam® Cup
1 Washer
*Deep Container (Bowl or Pitcher)
*Water
*You Must Provide
Procedure
Part 1
1. Fill the container with about four inches of water.
2. Find an open space outside to walk around in with the container of water in your hands.
3. Perform the following activities and record your observations of each motion in Table 1:
a. Start with the water at rest (e.g., on top of a table). Grab the container and quickly accelerate it.
b. Walk with constant speed in a straight line for 15 feet.
c. After walking a straight line at constant speed, make an abrupt right-hand turn. Repeat with a left-hand turn.
d. After walking a straight line at constant speed, stop abruptly.
Part 2
1. Place a 3 x 5 notecard on top of a Styrofoam® cup.
2. Place a washer on the middle of the 3 x 5 notecard.
3. Hole the Styrofoam® cup with your non-dominant hand and flick the notecard with your dominant hands (the hand you write with) so it moves off of the Styrofoam® cup. Record your observations in Table 2.
4. Repeat Steps 1- 3 four times for a total of five trials.
Table 1: Motion of Water Observations
Motion Observations
a Water rises up the back of the cup (towards you)
b No movement of water
c Water rises up left side of the cup when turning right, and up right side of the cup when turning left (i.e water rises in opposite of direction of turn)
d Water rises in front of cup (away from you)
Table 2: Observations After Flicking Notecard Off of Cup
Trial Observations
1 Card flies off of cup, washer goes in the cup
2 Card goes up in the air & off of cup, washer goes on the floor
3 Card flies off of cup, washer goes in the cup
4 Card flies off of cup, washer goes in the cup
5 Card flies off of cup, washer goes in the cup
Post-Lab Questions
1. Explain how your observations of the water and washer demonstrate Newton’s law of inertia.
2. Draw a free body diagram of your containers of water from the situation in Part 1 Step 4d. Draw arrows for the force of gravity, the normal force (your hand pushing up on the container), and the stopping force (your hand accelerating the container as you stop.) What is the direction of the water’s acceleration?
3. Can you think of any instances when you are driving or riding a car that are similar to this experiment? Describe two instances where you feel forces in a car in terms of inertia.
Experiment 2: Newton’s Third Law and Force Pairs
In this experiment, you will investigate Newton’s Third Law of Motion by observing forces exerted on objects.
Materials
5 N Spring Scale
10 N Spring Scale
(2) 30 cm Pieces of String
0.5 kg Mass
Pulley
Procedure
Part 1
1. Make sure the spring scales are calibrated using the standard masses.
2. Hook the handle of the 5 N spring scale to the hook of the 10 N spring scale.
3. Holding the 10 N spring scale stationary, pull the hook of the 5 N spring scale until the force reads 5 N on it. Record the force on the 10 N spring scale in Table 3.
4. Repeat Steps 2 and 3 with the 10 N spring scale hanging from the 5 N spring scale. Record the force on the 5 N spring scale in Table 3.
Part 2
1. Suspend the 0.5 kg mass in the air using the 10 N spring scale. Record the force on the 10 N spring scale in Table 4.
2. Tie one end of one of the pieces of string to the 0.5 kg mass and the other end to the hook of the 10 N spring scale.
3. Suspend the mass in the air by lifting the 10 N spring scale. Record the force on the 10 N spring scale in Table 4.
Table 3: Force on Stationary Springs
Force on Stationary 10 N Spring Scale (N)
5 N
Force on Stationary 5N Spring Scale (N)
5 N
Figure 5: Pulley Set Up
4. Untie the end of the string attached to the 0.5 kg mass and tie it to the hook of the 5 N spring scale.
5. Hook the 0.5 kg mass to the handle of the 5 N spring scale. Suspend the mass, scales, and string by holding the handle of the 10 N spring scale. Record the values of the spring scales in Table 4.
6. Secure the pulley on a table top by tying string to one of the hooks. Then, use masking tape to secure the string to a table top so that the hook on the top of the pulley lays flat on the side of the table top (Figure 5).
7. Using the mass setup from Step 5, place the string over the pulley by unhooking one of the spring scales, feeding the string through the pulley and reattaching the string to the hook of the spring scale (Figure 6).
8. Hold the 10 N spring scale in place so that the scales and mass are stationary. Record the values for both spring scales in Table 4.
Figure 6: Step 7 reference (string length and mass may vary).
Table 4: Spring Scale Force Data
Suspension Set Up Force (N) on 10 N Spring Scale Force (N) on 5 N Spring Scale
0.5 kg Mass on 10 N Spring Scale 5 N 5 N
0.5 kg Mass with String on 10 N Spring Scale 5 N
0.5 kg mass, string and 5 N Spring Scale on 10 N spring scale 0.4 N 5 N
0.5 kg mass, string and 5 N Spring Scale on 10 N spring scale on Pulley 0 N 5 N
Post-Lab Questions
1. How did the magnitude of the forces on both spring scales compare after you moved the 10 N spring scale?
2. How did the magnitude of the forces on both spring scales compare after you move the 5 N spring scale?
3. Use Newton’s 3rd Law to explain your observations in Questions 1 and 2.
4. Compare the force on the 10 N spring scale when it was directly attached to the 0.5 kg mass and when there was a string between them.
5. Compare the force on the two spring scales in Steps 5 and 6. What can you conclude about the tension in a string?
Experiment 3: Newton’s Second Law and the Atwood Machine
This experiment will demonstrate the mechanical laws of motion using a simple assembly named the Atwood machine that is similar to that used by Rev. George Atwood in 1784 to verify Newton’s Second Law.
Materials
Masking Tape
2 Paperclips
Pulley
5 N Spring scale
Stopwatch
String
Tape measure
15 Washers
Procedure
Part 1
1. Support the pulley so that objects hanging from it can descend to the floor. Do this by tying a short piece of string to one of the pulley hooks. Use a piece of masking tape to secure the string to a table top or door frame so that the pulley hangs plumb (Figure 5).
Note: A higher pulley support will produce longer time intervals which are easier to measure.
2. Thread a piece of string through the pulley so that you can attach washers to both ends of the string. The string should be long enough for one set of washers to touch the ground with the other set near the pulley. (You may attach the washers using a paperclip or by tying them on).
3. Use the spring scale to weigh the set of fifteen washers. Divide the total mass by fifteen to find the average mass of a washer. Record the total mass of the washers and average mass of one washer in Table 5.
4. Attach seven washers to each end of the string.
5. Observe how the washers on one side behave when you pull on the washers on the other side.
6. Add the remaining washer to one end of the string so one side of the string has seven washers (M1), and the other has eight washers attached to it (M2). Answer Post Lab Question 1 based on your observations.
7. Place M1 on the floor. Use the tape measure to measure the height that M2 is suspended while M1 is on the floor. Measure the distance M2 will fall if you release the light set when it is in contact with the floor. Record the distance in Table 5.
8. Time how long it takes for M2 to reach the floor. Repeat Steps 7-8 four more times (five times total), recording the values in Table 5. Calculate the average time.
9. Calculate the acceleration (assuming it is constant) from the average time and the distance the washers moved.
Part 2
1. Transfer one washer, so that there are six on one end of the string (M1) and 9 on the other (M2).
2. Determine the mass on each end of the string.
3. Place the M1 on the floor. Measure the height that M2 is suspended at while M1 is on the floor. Measure the distance M2 will fall if you release the light set when it is in contact with the floor.
4. Time how long it takes for the heavy set of washers to reach the floor. Repeat Steps 3-4 five times, recording the values in a table and then calculate the average time.
5. Calculate the acceleration (assuming it is constant) from the average time and the distance the washers moved.
Table 5: Motion Data
Mass of 15 Washers
(kg) 40 g Average Mass of Washer (kg) 2.67 g
Procedure 1
Height (m): 25”
Trial Time(s)
1 2.11
2 1.86
3 1.73
4 1.83
5 2.06
Average 1.918 s
Average Acceleration (m/s2) 0.66 m/s^2
Procedure 2
Height (m): 24.5”
Trial Time(s)
1 0.91
2 0.81
3 0.88
4 0.88
5 0.93
Average 0.882
Average Acceleration (m/s2) 1.41 m/s^2
Post-Lab Questions
1. When you give one set of washers a downward push, does it move as easily as the other set? Does it stop before it reaches the floor. How do you explain this behavior?
2. Draw a free body diagram for M1 and M2 in each procedure (Procedure 1 and Procedure 2). Draw force arrows for the force due to gravity acting on both masses (Fg1 and Fg2) and the force of tension (FT). Also draw arrows indicating the direction of acceleration, a.
3. Use Newton’s Second Law to write an equation for each of the free body diagrams you drew in Question 2. (Note: Be sure to use the correct signs to agree with your drawings). Solve these four equations for the force of tension (FT). You answer should be in variable form.
4. Set the two resulting expressions for the force of tension equal to one another (as long as the string does not stretch, the magnitude of the acceleration in each equation is the same). Replace Fg1 and Fg2 with M1 and M2, respectively. Solve the resulting equation for a. Then, go back to Question 3 and solve for the FT.
5. Calculate the acceleration for the two sets of data you recorded and compare these values to those obtained by measuring distance and time using percent error. What factors may cause discrepancies between the two values?
6. Calculate the tension in the string for the falling washers. From these two values, and the one where the masses were equal, what trend do you observe in the tension in the string as the acceleration increases?
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