Question

Write a hypothesis for Part II of the lab, which is about the relationship described by F = ma. In the lab, you will use a toy car and apply forces to it. Use the format of "if . . . then . . . because . . .” and be sure to answer the lesson question "How can Newton's laws be experimentally verified?” specific to Newton’s second law.

Answer 1

If the net horizontal force applied to the toy car is increased while the car's mass is held constant, then the car's acceleration will increase proportionally (for example, doubling the applied force will double the acceleration), because according to Newton’s second law a = F/m — acceleration is directly proportional to net force and inversely proportional to mass.

How Newton’s second law can be experimentally verified in this lab:
- Hold the car’s mass fixed and apply several different known net forces (e.g., with calibrated weights, a spring scale, or varying pull force).
- Measure the resulting acceleration for each force (using a motion sensor, ticker timer, or time to travel a fixed distance).
- Plot acceleration (a) versus net force (F). If Newton’s second law holds, the plot will be a straight line through the origin with slope 1/m.
- Alternatively, hold force constant and vary the car’s mass; plot a versus 1/m and expect a linear relationship.
- Account for and minimize systematic effects (friction, inclines, air resistance) and repeat trials to estimate uncertainties; agreement of the measured proportionality with the predicted 1/m (within experimental error) confirms F = ma.