Science Unit D

Question 1

A machiene

Answer 1

A device that helps us do work.

Question 2

A simple machiene

Answer 2

is a tool or device made up of one basic machine

Question 3

How many simple machines are their?

Answer 3

There are six simple machines that help us do work: the lever, inclined plane, wedge, screw, pulley, and wheel and axle.

Question 4

Lever

Answer 4

The lever is a rigid bar or plank that can rotate around a fixed point called a pivot or fulcrum. Levers are used to reduce the force needed to carry out a task such as pulling a nail, opening a bottle, hitting a baseball, and cutting paper

Question 5

First class lever

Answer 5

A first-class lever has the fulcrum between the load and the point where the effort is exerted to move the load.

Question 6

A second class lever

Answer 6

A second class lever has the load between the effort and the fulcrum.

Question 7

A third class lever

Answer 7

A third class lever has the effort between the load and the fulcrum.

Question 8

Inclined plane

Answer 8

An inclined plane or ramp would make it easier for you to move the box up onto the desk. An inclined plane makes it possible to lift heavy objects using a smaller force.

Question 9

Wedge

Answer 9

A wedge is similar in shape to an inclined plane, but it is used in a different way. The wedge machine is forced into an object. By pressing on the wide end of the wedge, you can exert a force on the narrow end so it splits an object apart.

Question 10

Screw

Answer 10

A screw is a cylinder with a groove cut in a spiral on the outside. Using a screw helps you increase the force you use. It can penetrate materials using a relatively small force. A screw can also be used for converting rotational (turning) motion to linear motion (motion in a straight line).

Question 11

Pulley

Answer 11

A pulley consists of wire, rope, or cable moving on a grooved wheel. Pulleys may be made up of one or many wheels and can be fixed in place or movable. They can be linked together in systems for moving and lifting objects

Question 12

Wheel & Axl

Answer 12

The wheel and axle are a combination of two wheels of different diameters that turn together. A longer motion on the wheel produces a shorter but more powerful motion at the axle. The steering wheel and steering column in a car together form a wheel and axle. That combination is one example of using a wheel and axle to increase the size of a force

Question 13

Complex machine

Answer 13

Most of the devices that we use today are made up of several simple machines. These devices are called complex machines. A complex machine is a system in which simple machines all work together

Question 14

System

Answer 14

A system is a group of parts that work together to perform a function.

Question 15

Subsystem

Answer 15

Within the bicycle are groups of parts that perform specific functions, such as braking or steering. These groups of parts are called subsystems. They consist of 1 simple machine

Question 16

Linkage

Answer 16

The linkage is the part that transfers your energy from the pedals to the back wheel. In a bicycle, the chain is that linkage.

Question 17

Transmission

Answer 17

Most machines that move objects are more complex than a bicycle. They usually move much larger loads than just one person. These machines use a special type of linkage called a transmission to transfer the energy from the engine to the wheels

Question 18

Gears

Answer 18

Gears are essential components of most mechanical systems. They consist of a pair of wheels that have teeth that interlink. When they rotate together, one gearwheel transfers turning motion and force to the other

Question 19

mechanical advantage

Answer 19

The mechanical advantage of a machine is the amount by which a machine can multiply a force.

Question 20

Input force

Answer 20

The force applied to the machine is called the input force

Question 21

Output force

Answer 21

The force the machine applies to the object is called the output force

Question 22

Calculating mechanical advantage

Answer 22

MA = Output force/input force

Question 23

Speed ratio

Answer 23

A measure of how the speed of the object is affected by a machine is called the speed ratio

Question 24

Calculating speed ratio

Answer 24

SR = Input distance/output distance

Question 25

Friction

Answer 25

Friction is a force that opposes motion. Friction is caused by the surface roughness of materials. A rough surface creates more friction than a smooth one

Question 26

Efficiency

Answer 26

Efficiency is a measurement of how well a machine or device uses energy

Question 27

Calculating efficiency

Answer 27

E = Mechanical advantage/speed ratio times 100

Question 28

Work

Answer 28

work is done when a force acts on an object to make the object move

Question 29

Calculating work

Answer 29

W = F times D
W = Force times Distance

Question 30

Pressure

Answer 30

pressure is a measure of the amount of force applied to a given area