Both change rotational speed and direction of force
Gears are classified as simple machines that are designed to be used to change the magnitude (size) and direction of force. Multiple gears in succession can be used to change rotation speed, as well as torque. Certain gear arrangements can result in mechanical advantage, meaning that they are considered simple machines. This is dependent on the gear ratio.
B Change rotational speed
C Change direction of force
D Decrease mechanical advantage