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# Systems in Action

Question | Answer |
---|---|

What is the definition of mass? | Mass is the amount of matter in an object. |

What is the metric unit for measuring mass? | The metric unit for measuring mass is the kilogram (kg) |

What unit are smaller masses measured in? | Smaller masses are measured in grams (g) |

Does your mass on Earth change if you go to the moon? Give an example. | No objects mass does not change if it goes to the moon. For example if you have a mass of 50 kg on earth you will have a mass of 50 kg on the moon. This is because you still take up the same smount of space. |

What is the definition of weight? | Weight is the amount of force on an object due to gravity. Therefore, weight means the same thing as force of gravity |

Explain the relationship between weight and the force of gravity. Give and example. | Since the force of gravity on Earth is about six times stronger than the force of gravity on the Moon, your weight is about six times stronger on Earth as it is on the Moon. |

Name a tool that can be used to calculate weight. | Spring scales show the weight of an object in Newtons |

What is the formula to calculate weight(force of gravity)? | Force of Gravity=(mass of object) x (the strength of the Earthâs gravitational field) |

What is the strength of the Earthâs gravitational field per kilogram? | 9.8 N/kg (9.8 Newtons per kilogram) |

What is the definition on Work? | Work is the amount of effort spent when a force causes an object to move. |

How do you calculate work? | The formula for work is... (Work in Joules = (force in Newtons) x (distance in meters) |

What is the definition of Energy? | Energy is defined as the ability to do work. |

What is the metric unit for Energy? | The metric unit for Energy is joule(s) (J) |

What is the difference between kinetic and potential energy? | Kinetic energy is when an object is moving whether as potential energy is energy stored to do work later in time. |

What is gravitational potential energy? | The potential energy of an object that is able to fall is called gravitational potential energy. |

What is the need for machines? | When you use machines you are lowering the amount of work that you need to do. For example if you needed to remove a nail with your hands, you would need to work more, but if you use a hammer to do it less work is needed. |

How do you calculate mechanical advantage? | To calculate mechanical advantage you divide the output force in Newtons by the input force in Newtons. MA=F out divided by F in |

What are the functions of machines(how do they make work easier)? | Machines make work easier in three ways: 1. By increasing the force that can be applied to an object 2. By increasing the distance over which the force is applied 3. By changing the direction of force |

How do you calculate ideal mechanical advantage? | The mechanical advantage of a machine that has no friction is called the ideal mechanical advantage (IMA) Ideal Mechanical Advantage=input distance divided by output distance IMA=d in divided by d out |

Explain some forces in use when a machine is at work. | Whenever a machine is used to do work, two forces are always involved. When you extert a force on the machine(input force), the machine exterts a force on the object(output force). For example, suppose you need to lift a car using a jack. |

What is a lever? | A lever is a rigid bar that is supported at one point. The point at which the bar is supported is called the fulcrum. |

What is a first-class lever? | There are two characteristics of a first-class lever: 1. The fulcrum is between the input and output force 2. The input force is opposite direction of the output force |

Give an example of a first-class lever and explain where the fulcrum, output force, and input force would be. | Example: Using a pry bar to remove the lid off of a paint can Fulcrum: Part of the pry bar that is touching the canâs rim Output Force: The tip of the pry bar, pushing the lid of the can upward Input force: Your hand, pushing down on the pry bar handle |

* this is not a question* Just letting you know that you will need to know how to draw all types of levers so you may want to practice on a blank piece of paper :) | |

What is a second-class lever? | There are 3 characteristics of a second-class lever 1. The fulcrum is at the very end 2. The output force is between the fulcrum and the input force 3. Input and output forces are in the same direction |

Give an example of a second-class lever, where the Fulcrum, Output force, and the Input force would be. | Example:Removing the cap from a soft-drink bottle Fulcrum: The very end of the opener that makes contact with bottle cap Output Force: Between the fulcrum and the input force Input Force: Your hand pulling up on the opener |

What is a third-class lever? Pt. 1 | There are 4 characteristics of a third-class lever 1. The input force is between the fulcrum and the output force 2. It always produces a mechanical advantage less than 1, because the output force is always less than the input force |

Give an example of a Third-class lever, where the Fulcrum, Output force, and the Input force would be. | Example: A garden rake (holding the rake) Fulcrum: where your left hand is holding the rake stationary at the top. Output force: The head of the rake applying force to the leaves Input Force: Your right hand that moves the rake |

How do you calculate the ideal mechanical advantage of a lever? | Ideal Mechanical Advantage = length of input arm divided by length of output arm IMA = L in divided by L out Refer to image on levers page to see what all levers look like and what L in and L out is |

What is a Third-class Lever? Pt.2 | 3. Distance and speed are always greater at the output end than at the input end 4. The input and output forces are in the same direction |