Newtons Second Law Essay Example

Newtons Second Law Essay To confirm the relationship between the net force applied to a body and the bodys acceleration.Background:This experiment has two parts; Part A: How does the acceleration of a trolley change as you change the weight of the total mass on a mass holder supported by a pulley?; Part B: How does the acceleration of a trolley change as you change the weight of the total mass on the trolley itself?When the trolley is released, it accelerates to the right due to the mass on the mass holder, passing through two light gates. A scalar timer connected to each light gate records the time taken for a card mounted on the glider to pass through the light gate The time recorded at the two light gates is used to calculate 2 different speeds of the glider, and hence the acceleration of the glider may be found.Equipment: Trolley, 2 light gates, 2 scalar timers, masses, string, card, ruler, electric scalePart A:Data Collection:Mass of Weight (g)Time (s)Trial 1Trial 2Trial 3Trial 4LG1LG2LG1LG2LG1LG2LG1LG2 300.840.440.870.450.850.440.860.44400.620.330.640.320.630.320.620.32500.520.280.530.270.530.270.530.27600.450.240.460.240.460.240.460.24700.420.220.420.220.410.210.410.21800.390.200.390.200.390.200.390.20900.370.190.360.190.360.190.360.191000.340.170.340.180.340.170.340.181100.320.170.320.170.320.170.320.171200.300.160.300.160.300.160.300.16Constants:Mass of car 607.8 gDistance between light gate 1(LG1) to light gate 2 (LG2): 30 cmCard length: 17 cmData Processing:To convert the masses to forces we must do the following. Since the measurements are taken in grams we need to divide by 1000. This makes our measurements change to kilograms. After that we need to multiply by 9.8 because 1 kg is 9.8 N.Mass of Weight (g)Force (N)300.29400.39500.49600.59700.69800.78900.881000.981101.081201.18Since we have more than one trial for each mass, we need to find the average times for each mass.Average Times:Force (N)LG1 Time (s)LG2 Time (s)0.290.860.440.390.630.320.490.530.270.590.460.240.690.420. 220.780.390.200.880.360.190.980.340.181.080.320.171.180.300.16If then to calculate the velocity we will take the length of the card (17 cm) which is d, and divide it by the average times.Velocities:Force (N)LG1 Velocity (ms-1)LG2 Velocity (ms-1)0.290.200.380.390.270.530.490.320.620.590.370.710.690.410.790.780.440.850.880.470.890.980.500.971.080.531.001.180.571.06To calculate the acceleration we will need to use the following equation for motion:The next step is to make a (acceleration) the subject of the equationThis means that, where v is final velocity, u is initial velocity, and s is the distance traveled which is a fixed value of 30 cm (Distance between Light Gate 1 and Light Gate 2)Acceleration:Force (N)Acceleration (ms-2)0.290.180.390.340.490.480.590.610.690.760.780.890.880.970.981.161.081.201.181.35There is a linear relationship in this graph; this shows that the net force is directly proportional to the acceleration.Part B:Data Collection:Additional Mass of Cart (g)Time (s)T rial 1Trial 2Trial 3Trial 4LG1LG2LG1LG2LG1LG2LG1LG200.390.200.390.200.400.200.400.20500.420.210.430.220.420.210.430.221000.460.230.460.230.450.230.450.231500.490.250.500.250.490.250.490.252000.510.260.500.250.520.270.510.262500.540.280.550.280.540.280.550.283000.580.290.570.290.590.290.570.293500.610.310.610.310.610.310.610.314000.660.340.650.330.660.350.650.344500.790.390.780.390.800.400.780.38Constants:Mass of car: 407.7 gDistance between light gate 1(LG1) and light gate 2 (LG2): 30 cmCard length: 17 cmMass on Pulley: 50 gData Processing:Mass of Cart:To find the mass of the cart we need to add the initial mass of the cart to the additional mass added onto it. We also need to convert this number into kilograms.Additional Mass on Cart (g)Mass of Cart (g)Mass of Cart (kg)0407.70.4150457.70.46100507.70.51150557.70.56200607.70.61250657.70.66300707.70.71350757.70.76400807.70.81450857.70.86Since we have more than one trial for each mass, we need to find the average times for each mass.Av erage Times:Mass of Cart (kg)LG1 Time (s)LG2 Time (s)0.410.400.200.460.430.220.510.460.230.560.490.250.610.510.260.660.550.280.710.580.290.760.610.310.810.660.340.860.790.39If then to calculate the velocity we will take the length of the card (17 cm) which is d, and divide it by the average times.Velocities:Mass of Cart (kg)LG1 Velocity (ms-1)LG2 Velocity (ms-1)0.410.430.850.460.400.790.510.370.740.560.350.680.610.330.650.660.310.610.710.290.590.760.280.550.810.260.500.860.220.44To calculate the acceleration we will need to use the following equation for motion:The next step is to make a (acceleration) the subject of the equationThis means that, where v is final velocity, u is initial velocity, and s is the distance traveled which is a fixed value of 30 cm (Distance between Light Gate 1 and Light Gate 2)Acceleration:Mass of Cart (kg)Acceleration (ms-2)0.410.900.460.770.510.680.560.570.610.520.660.460.710.440.760.370.810.300.860.24Since we are getting a hyperbola shape in the graph, we will try to graph Mass of Cart vs. Acceleration-1 to get a linear relationship.I think that the last two points are outliers and they have been subject to lots of error. This is why I will draw the graph again without including them in the trend line.These graphs show that the mass of the cart is inversely or indirectly proportional to the acceleration. This means that the mass of the cart is directly proportional to the inverse of the acceleration.Conclusion and Evaluation:Figure 1Figure 2The aim of this lab is to confirm the relationship between the net force applied to a body and the bodys acceleration. The experiment has two parts: Part As aim is to see how the net force applied to a body affects the acceleration and Part Bs aim is to see what happens to the acceleration as you increase the mass of the cart.Obviously, the higher the net force on a body, the larger its acceleration. This is the obvious thing we found out from part a. In part B we found out that as the mass of the cart increased, its acceleration decreased. This is where the errors come in.This experiment was designed in a way the friction would be very minute or inexistent. The first set-up is using an air track; this allows the vehicle to move freely without friction due to a cushion of air being blown through the air track. The second set-up is using a friction compensated runway; this runway cancels out the effect of friction. However, our set-up included friction; this means that our results are distorted. The other thing is that all the values for the acceleration are lower than the actual value. This is because of Friction; all these calculations neglect the effect of friction. Friction makes a body move slower, slow moving bodies have a large inertia, so all the values of Mass are larger than the actual value.Assume there are two bodies, body A and body B. They are traveling on different surfaces but are pushed with the same force. Body A has a smaller net force than body B; there fore you assume that Body A has a larger mass than Body B or Body B has a larger acceleration than Body A. What if I told you that this is not the case? Maybe Body A and Body B have the same mass, what would you think? It would be logical to think that there are other forces acting on the system, Friction. Body A is traveling on a wooden surface (friction is present), Body B is traveling on a slippery, frictionless surface (friction is not present). So Body A doesnt have a larger mass than Body B, its just the surfaces that make us think so. This is the same here; these calculations assumed that friction was something else, which is why there are absurd numbers.If then imagine that a tension force of 1 N is acting on a body which is accelerating a 5 meters per second squared. and and This means the mass of the body equals 0.2 kilograms. What is happening in our situation is that our acceleration is smaller than it should be due to the other forces acting on the cart, like friction a nd air resistance. For example, instead of 5 ms-2 it is 4ms-2. This causes for there to be an error in our calculations.and and . This means the mass of the body is 0.25 kilograms- but its not. This value is larger than the real value, and this is exactly what is happening to us.The same problem exists in Part B. The net force is always less than the real value, 0.49 N. This is due to the other forces acting on the body like friction and air resistance., in part B the net force is always constant and the mass and acceleration are always changing. Since the acceleration is going to be smaller than it should be (due to the other forces acting on the body) the net force will also be smaller than it should be.The other problem with including friction comes in part B. When you add weights on the cart, you increase the force of gravity acting on the cart and the force of normal reaction acting on the cart (Figure 2). But, as you increase the mass of the cart you push the cart and make it come closer to the surface it is in contact with. This increases the force of friction and makes is increase as you increase the mass of the cart.The other (smaller) errors in our lab were the following. Firstly, the way we released the weight that would pull the cart was different each time, there is no way of keeping that the same no matter how hard we try. Secondly, we drew a line that shows where we are supposed to release the cart; the cart will never be in the same position as it was the first time we released it. Finally, we did this lab in two sittings, this means the environment changed and we had to make some adjustments, this affected the accuracy of our lab.To ensure the accuracy of our lab we did many things. Firstly, we measured the distance between the light gates more than one and between trials. Secondly, we made sure that the light gates were placed parallel to the edge of the counter. Also, we drew a line that would show us where we should release the cart. Next, we did four trials instead of three or one trial. We weighed the cart more than once and we measured the length of the card more than once as well. Finally, we tried to keep the lab as accurate as possible by doing the same jobs each time because everybody does their own job in their own way and if that way was kept constant than our results would be more accurate.Next time, we will use a different set-up, preferably with an air-track and a very streamlined glider. We will take even more accurate measurements so that our data would be even more accurate than it is. We will make sure we are releasing the cart from the same place each time, even if it means we need to use a magnifying glass. We will also try to do this lab in one sitting. Finally, we will try to come up with a way in which we will release the cart so that it would be the same each time.