Newton’s 2nd Law Lab
Purpose:
F=ma
Force- the block that drops to the ground
Mass- the car
Acceleration- the force of the block is increasing so the car will increaseaccelerate
Hypothesis
I think that when the force increases, the acceleration of the car increases. The car accelerates because
Newton states in his second law that the acceleration of an object depends on its mass, and the force acting
upon it. In this case the mass stayed the same throughout the experiment, so the force was the only thing
affecting the acceleration of the cart, therefore the more force acting on the cart, the more it would accelerate.
Distance= .80 meters
Acceleration lab
W= mg
Newton’s Second Law
F=ma
m=F/a
a = F/m
Weight = W Weight is a force Weight is mass times gravity
Gravity is an acceleration unit. On Earth, gravity is 9.8 m/s/s
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The F or Force will pull on the cart, the mass is the cart and the acceleration is the motion of the cart that
will be measured by distance known and stopwatch.
Materials: cart, string, masses of 100, 200 and 300 grams, meterstick, tape, stopwatch, pulley and clamp to
attach it to table
Procedure:
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1. Mark off a distance of 0.80m on lab table.
2. Apply a 100g mass to end of string and loop over the pulley
3. Have a partner hold the front edge of the cart at the starting line.
4. Release the skateboard when timer is ready.
5. Determine how long it takes for front wheels of cart to reach the finish line.
6. Record on table.
Repeat steps 1-6 two more times for an average time.
Record data in columns labeled trial 2 and 3
Repeat steps with a 200g mass
Repeat steps with a 300g mass
Data table What is the weight in Newtons of a 100g mass?
Brass 100 g mass must be converted to a FORCE OR WEIGHT. It will move the cart, so will the 200g and 300g.
100 g x 1kg/1000g =.1 kg
.1kg X 9.8 m/s/s= .98 N
200g x
.2kg X 9.8m/s/s= 1.96 N
300g x
.3kg X9.8 m/s/s= 2.94 N
Place these calculated values in the table below in the first column. Then read the directions below the chart to
complete the chart correctly.
F (N)
.98
1.96
2.94
Trial 1
Time (s)
1.78
1.40
1.10
Trial 2
Time (s)
1.59
1.22
.96
Trial 3
Time (s)
1.56
1.15
1.04
Avg
TIme
1.64
1.26
1.0
Avg
Velocity (m/s)
.49
.63
.80
Final
Velocity m/s
.98
1.26
1.6
Acceleration
m/s/s
.60
1.00
1.6
Calculations and table:
1.
2.
3.
4.
For each force you used, find the average of the three times that you measured. Record the average in
data table.
Find the average velocity for the cart for each force. Use this formula: avg v= 0.8m / avg t in seconds.
Record result in data table.
For final velocity; multiply each average velocity by 2. Record the result in data table.
For acceleration; divide each final velocity by the average time. Record in table.
Graph: Make a line graph. Show acceleration on the y-axis and force on the x-axis. The y-axis scale should go from
zero to about 1/m/s/s. The x –axis should go from zero to 3 Newtons.
Graph go to programs on the start button and use graphical analysis program to make a graph of the two variables
that were tested and measured; dependent and independent variable?
Independent- force
Dependant- acceleration
Conclusions: relationship of variables in Newton’s second law? The model is the equation and how it is organized
to inform or show relationship.
Does graph show relationship of variables clearly? How is the acceleration related to the pulling force?
Yes, it’s a direct relationship. The more force pulling on the car, the more the car accelerates. The graph
shows clearly that the more force applied to the cart, the more the car would accelerate. This is shown by the
steady positive line on the graph.
Critique work:
What is questioned? Wonder about ??? Does this apply to ?
In this experiment, we were questioning whether or not, changing the force acting upon the car, would
change, by increasing or decreasing, the acceleration of the car. We were looking to see if there was in fact a
correlation between the force put on the car and the acceleration of the car. I wonder what would happen if we
had performed this experiment on the moon. The mass of the car would be the same because gravity affects
weight not mass. So I wonder if because of this our results would have been the same as they were on earth.
We found that our hypothesis was correct in that the more force pulling the car, the more the car accelerated.
We can apply this to Newton’s second law because he stated that only two things affect acceleration and they
are mass of an object, and the force acting upon that object. In this case our mass stayed the same, so the
changing force acting on the cart, directly caused the change in acceleration. One thing I wondered was what
would have happened if we had performed this experiment on the moon. The mass of the car would be the
same because gravity affects weight not mass. So I wonder if because of this our results would have been the
same as they were on earth.
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Experiment done by: Rebecca Goldstein, Alexandra Braun, Martin Gross and, Ryan Bauman
HW: complete lab and its parts and questions and do the following:
Design an experiment:
Design an experiment to test how the acceleration of the loaded skateboard depends on its mass. Think about how
you would vary the mass of the cart. What quantity would you need to measure that you did not measure in this
experiment? What equipment would you need to make that measurement? Any other equipment needed that was
not needed for this experiment?
To test how the acceleration of the loaded skateboard would depend on mass you would need to have
the mass of the cart change, while the force pulling the cart forward would need to stay the same throughout
the experiment. The experiment would be set up almost exactly the same way as the previous one however to
change the mass of the cart, we would take the mass blocks we used in our previous experiment and put them
on top of the cart, and instead of changing the force that is pulling the cart the whole time, we would keep it the
same. First we would put a mass of 100g or .98 N on the cart, and do three trials, with a constant force pulling
the cart of 100g. After, we would replace the 100g mass block with a 200g or 1.96 N mass block and test that
three times. We would do this one last time with a block with a mass of 300g or 2.94 N.
Throughout each trial we will be keeping time in seconds of the cart when it starts moving to when it stops and
recording this data. The force acting on the cart to pull it forward will remain at 100g throughout the entire
experiment. In this new experiment we would need to measure acceleration, which is force divided by mass. In
this case, the force would be the weight 100g pulling on the car, and the mass would be the varying block’s mass
that we would put on the cart. We would use the same exact equipment that was used during the previous
experiment; however we will operate the procedures differently.
Procedure:
1.
Mark off a distance of 0.80m on lab table.
2.
Apply a 100g mass block to end of string and loop over the pulley
3.
Apply a 100g mass block on top of the cart
4.
Have a partner hold the front edge of the cart at the starting line.
5.
Release the skateboard when timer is ready.
6.
Determine how long it takes for front wheels of cart to reach the finish line.
7.
Record on table.87.
8.
Do this 2 more times
9.
Replace 100g mass block on the cart with a 200g mass block and repeat steps 3-7
10.
Replace 200g mass block on the cart with a 300g mass block and repeat steps 3-7