Wheels, Axles, and Rotation Flashcards

Three gears are in a row: Gear 1 meshes with Gear 2, and Gear 2 meshes with Gear 3. All three gears have the same number of teeth. If Gear 1 rotates clockwise, which direction does Gear 3 rotate?

Answer: Clockwise

Each meshing gear reverses direction; Gear 1 (CW) → Gear 2 (CCW) → Gear 3 (CW), so Gear 3 rotates clockwise like Gear 1.

A winch drum (axle) has a radius of 3 inches and its handle (wheel) has a radius of 18 inches. What is the mechanical advantage?

Answer: 6

Mechanical advantage of a wheel-and-axle = wheel radius / axle radius = 18/3 = 6.

A conveyor belt runs over two rollers of equal diameter. If the left roller is the drive roller turning clockwise (viewed from the front), the belt's top surface moves:

Answer: To the right

A clockwise left drive roller pulls the top of the belt toward the right, moving items on the belt surface to the right.

Two wheels of different sizes are connected by an axle (fixed together). A rope is wrapped around the larger wheel and a load hangs from a rope on the smaller axle. When the larger wheel is turned, the load:

Answer: Rises with less input force than the load's weight

The large wheel provides mechanical advantage: input force × wheel radius = load × axle radius, so less force is needed than the load's actual weight.

A wheel is spinning and the brake is applied to slow it down. The braking force acts at a radius of 10 inches from the center. To achieve the same stopping torque with a brake pad placed only 5 inches from the center, you would need:

Answer: Twice the braking force

Torque = Force × radius; to keep torque constant when radius is halved, force must double: F × 5 = F₀ × 10, so F = 2F₀.

A vehicle's odometer measures distance traveled based on wheel rotations. If a driver replaces standard tires (circumference 80 inches) with larger tires (circumference 100 inches), the odometer will:

Answer: Underestimate the distance traveled

Each rotation now covers 100 inches instead of 80, but the odometer still counts rotations as if each were 80 inches, so it reads less distance than actually traveled.

A water wheel turns a millstone via a system of wooden gears. The water wheel has 60 teeth and the millstone pinion has 10 teeth. The water wheel turns at 5 RPM. At what speed does the millstone turn?

Answer: 30 RPM

Speed ratio = driver teeth / driven teeth = 60/10 = 6; millstone speed = 5 × 6 = 30 RPM.