Physics 211 Experiment 4 Newtons Second
Physics 211 Experiment #4 Newton’s Second Law – Atwood’s Machine
Newton’s second law (FNET = ma) can be experimentally tested with an apparatus known as an “Atwood’s Machine” (See Figure 1.) Two weights of unequal mass, connected by a thread, are draped over a pulley, as shown in the figure. When released, the larger mass accelerates downward and the smaller one accelerates upward.
Figure (1a): The Atwood’s Machine, showing the pulley and the two masses after a run.
Figure (1b): A close up of the pulley and one of the masses after a run.
Figure (2a): A schematic diagram of the apparatus shown in Figure 1.
Figure (2b): The free body diagram for M1.
Figure (2c): The free body diagram for M2. Newton’s Second Law applied to the larger mass, M2, implies (see Figure 2c):
FNET(on M2) = M2a
T – M2g = – M2a (1)
Newton’s Second Law applied to the smaller mass, M1, implies (see Figure 2b):
FNET(on M1) = M1a
T– M1g = M1a (2)
The tension T can be eliminated from equations (1) and (2) obtain:
M2g – M1g = M2a + M1a (3)
The magnitude of the acceleration, a, of the system is then:
(4)
The numerator, (M2 – M1)g, is the net force causing the system to accelerate. The denominator, (M2 + M1), is the total mass being accelerated. Equation (4) can be written:
(5)
Where FNET = (M2 - M1) g
And MTOTAL = (M2 + M1)
Apparatus
Pasco 750 Interface 10 spoke smart pulley (Pasco ME 9387) with stereo phone plug Table clamp for pulley Two 5 gram mass holders Masses: 2 x 100gm, 3 x 50gm, 2 x 20gm, 2 x 10gm, 2 x 5gm Thread
Detailed Procedure and Analysis for Atwood’s Machine Experiment
I. Set-up of computer and interface 1. Turn on the PASCO 750 interface first. Verify that the indicator light is on.
2. Turn on the computer, and login.
3. Follow the instructions on the "Data Studio Information Sheet" to set up the computer for the experiment.
4. When you must choose the sensor,
Newton’s second law (FNET = ma) can be experimentally tested with an apparatus known as an “Atwood’s Machine” (See Figure 1.) Two weights of unequal mass, connected by a thread, are draped over a pulley, as shown in the figure. When released, the larger mass accelerates downward and the smaller one accelerates upward.
Figure (1a): The Atwood’s Machine, showing the pulley and the two masses after a run.
Figure (1b): A close up of the pulley and one of the masses after a run.
Figure (2a): A schematic diagram of the apparatus shown in Figure 1.
Figure (2b): The free body diagram for M1.
Figure (2c): The free body diagram for M2. Newton’s Second Law applied to the larger mass, M2, implies (see Figure 2c):
FNET(on M2) = M2a
T – M2g = – M2a (1)
Newton’s Second Law applied to the smaller mass, M1, implies (see Figure 2b):
FNET(on M1) = M1a
T– M1g = M1a (2)
The tension T can be eliminated from equations (1) and (2) obtain:
M2g – M1g = M2a + M1a (3)
The magnitude of the acceleration, a, of the system is then:
(4)
The numerator, (M2 – M1)g, is the net force causing the system to accelerate. The denominator, (M2 + M1), is the total mass being accelerated. Equation (4) can be written:
(5)
Where FNET = (M2 - M1) g
And MTOTAL = (M2 + M1)
Apparatus
Pasco 750 Interface 10 spoke smart pulley (Pasco ME 9387) with stereo phone plug Table clamp for pulley Two 5 gram mass holders Masses: 2 x 100gm, 3 x 50gm, 2 x 20gm, 2 x 10gm, 2 x 5gm Thread
Detailed Procedure and Analysis for Atwood’s Machine Experiment
I. Set-up of computer and interface 1. Turn on the PASCO 750 interface first. Verify that the indicator light is on.
2. Turn on the computer, and login.
3. Follow the instructions on the "Data Studio Information Sheet" to set up the computer for the experiment.
4. When you must choose the sensor,