A robotic arm in a packaging unit uses a motor, gears and a gripper to move heavy boxes from one conveyor belt to another.

(a) The gears transmit the motion and power generated by the motor to the robotic arm and the gripper through the interlocking of gear teeth.

(b) Two ways in which changing the gear ratio affects the force and speed of movement are:

1. Increasing the gear ratio, that is, using a driven gear with more teeth than the driving gear, increases the torque (force) available at the gripper but decreases the speed of movement. This is useful for lifting heavy boxes.
2. Decreasing the gear ratio, that is, using a driven gear with fewer teeth than the driving gear, increases the rotational speed of the arm but decreases the torque (force). This is useful for moving lighter boxes quickly.