Fichas
Unit 1.3 Wheels, pulleys and gears
Fichas del conjunto (21)
- 1What are the three things that wheels, pulleys, and gears increase?They increase the force we supply for a task, change the direction of a force or increase speed.
- 2What are the centre of a wheel and the outside of a wheel called?The centre of a wheel is called its axle and the outside of a wheel is its rim.
- 3What happens when you turn on a tap?When you apply a force to turn on a tap, the handle acts as a wheel.It increases the force you apply at its centre, allowing the spindle or axle to turn.
- 4What rotates faster the rim or the axle of a wheel?The rim of the wheel rotates with greater speed than the axle in its centre.As the wheel turns, the force at its centre is larger than the force at its rim.
- 5How does the electric fan operate really fast, although the motor of an electric fan turns the central axle slowly?The motor of an electric fan turns the central axle relatively slowly. This speed is multiplied through the spinning blades.The longer the blades, the greater the speed multiplied.
- 6How is a wheel used to produce a force advantage in a steering wheel?In a steering wheel, a wheel is used to produce a force advantage. The force applied to the steering wheel is increased at the axle of each wheel. The larger the steering wheel, the easier the axle is to turn.
- 7What is a pulley? and how can we increase the force applied to it?A pulley is a wheel with a groove around it into which a rope or chain can move. To increase the force applied, more than one pulley must be used.
- 8What happens when two pulleys are used?Using two pulleys halves the size of the effort force required, providing a mechanical advantage of 2.
- 9How can we produce a greater mechanical advantage using pulleys?A greater mechanical advantage can be produced using a number of pulleys in an arrangement called a block and tackle.
- 10What is the block and tackle arrangement?The block and tackle arrangement provide four times the force of a single pulley.
- 11What are gears and what is the most common type of gears?Gears are wheels that have teeth around their rim. The most common type of gears are called spur gears.
- 12What is a gear train and how does it works?A set of gears that are connected together is called a gear train. When one gear turns, the gear it interlocks with also turns, but in the opposite direction.
- 13What is a driving gear and a driven gear? and what combinations of gears increase force and speed?The gear that supplies the force is called the driving gear. The gear that is connected to this gear is called the driven gear. Different combinations of gears are selected to increase either the force applied or the speed of turning.
- 14Which gear combination acts as a force multiplier? How?If the driving gear is smaller than the driven gear, then the combination acts as a force multiplier.This combination results in a driven gear that rotates more slowly than the driving gear but does so with great force.
- 15Which gear combination acts as a speed multiplier? Example.If the driving gear is larger than the driven gear then the combination acts as a speed multiplier. Using gears as a speed multiplier are useful when using an eggbeater. Applying a greater force to the handle pays off as the beaters spin faster.
- 16What are the different types of gears and their functions?-Bevel gear
-Worm gear
-Rack and pinion
-Idler gear - 17Bevel gearsPositioned at right angles to each other so that they change the plane of rotation.
- 18Worm gearLooks like a screw, and is used to drive a gear, it's often used to reduce speed.
- 19Rack and pinionA gear wheel rotates over a row of teeth called the rack. This converts rotational motion into straight-line or linear motion
- 20Idler gearPositioned between a driving and a driven gear to get them rotating in the same direction.
- 21Calculate the gear ratio -: <<<<<<<<<Gear ratio = (number of teeth on driving gear ÷ number of teeth on the driven gear)
24÷12=2<<
