Force And Acceleration Essay

Investigating force and acceleration

Background

The relationship between force and acceleration is expressed by Newton’s second law of motion which states that “the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. “ (The Physics Classroom, n.d.)

This law can be expressed as the equation F= ma, where F is the net force, m is the mass and a is the acceleration. This equation can be used in different contexts and rearranged to solve numerous different calculations. Figure 1. Diagram of setup where a is acceleration, t is tension in the string, m is the mass of the brass masses and M(t)

This will be calculated by recording the time and the final velocity of the trolley using the installed photogates and using the formula a=(V-V_0)/t to find the acceleration.

Controlled variable How it will be controlled Why it should be controlled

The incline of the surface will be kept level. By keeping the air track level for all trials. Gravitational acceleration will accelerate the trolley if the air track is at an incline. This will cause skew in the results if not kept level.

Type of surface – air track Will be controlled by using the air track to reduce friction. Furthermore, the same setting of the air track will be used to make sure they have the same friction for each trial. Friction acts in the direction opposing motion. As friction increases, the acceleration decreases, causing negative skew in the results.

Mass of the trolley – 98.98g The same trolley will be used. Newton’s second law of motion states that more force is required to accelerate a greater mass.

Friction of the pulley The same pulley will be used. Friction between the string and the pulley, or within the pulley, will decrease the acceleration as it will act against the movement of the two masses.

It was observed that the acceleration of the trolley increased as the tension, or the force that pulled the trolley increased. This can be seen in Table 1 where the acceleration gradually increased from 2.9ms-2 at 0.22N to 7.0ms-2 at 0.65N of force.

It is seen on Graph 1 that the relationship between the two variables is a linear relationship with a strong correlation suggested by the R2 value of 0.94. The line of best fit must also pass through the origin to be considered directly proportional, which in this case, does not. This contradicts the Newton’s Second Law of Motion which states that force is directly proportional to acceleration when the mass is constant. However, the graph cuts the axis quite close to the origin and the difference can be attributed to error in the