In this volume, we will learn about the second law of motion. You can calculate the moving force required for given conditions of acceleration and mass using this law.

(1) Law of motion

2) The second law of motion

- A force applied to an object (movable body) causes it to accelerate in the direction of the force in proportion to the mass of the object.

- The relationship of force (F) and acceleration (A) can be described as F ∝ A.

- When "m" represents this proportional multiplier, the second law of motion can be expressed as F = m・A. This formula is called "equation of motion".

- The proportional multiplier (m) is the mass of the corresponding object.

- Therefore, reducing the weight of a movable body decreases the required force for moving the body. This means that a smaller motor can be adopted instead.

- The gravitational acceleration g (m/s²) acts on the mass m (Kg). The gravity applied to the object is calculated as W = m・g (N: Newton), which is the weight of the object.

- Depending on the load weight transported on the movable table, the required capacity of a rotary motor varies in order to generate the same acceleration in the linear drive mechanism.

- When the load mass in the left figure is m, the load mass in the right figure is three times more than m (= 3m), the driving force on the right needs to be three times more than the left mechanism in order to generate the same acceleration.

- Therefore, the weight reduction technique is required as an important technique for designing high-speed drive mechanisms.