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# Waves,Work,Power

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

What direction do waves travel? | Outward in all directions from the disturbance. |

Waves carry both energy and matter. True or False? | False- Waves only carry energy through a medium. |

What type of wave does not need a medium to carry energy from one place to another? | electromagnetic waves can travel through empty space |

If a firework went off in outer space, what would it sound like? | Nothing. Sound is a mechanical wave that needs a medium to travel through and in space there is no atmosphere for the sound waves to travel through. |

A high pitched sound would have a __________________ frequency. | high |

A loud sound would have a high _____________________. | amplitude |

Light traveling from the sun to Earth is an example of a(n) ___________ wave. | electromagnetic- it travels through empty space to get here (not requiring a medium) |

How would you describe the wavelength of a very low pitched sound? | A low pitched sound would have longer wavelengths because the frequency is low. |

What is frequency? | Frequency is how often waves pass a point in a given amount of time. It is measured in Hertz (waves per second). |

What is amplitude? | Amplitude is a measure of how much energy is carried in a wave. The further the distance from the crest/trough to the resting point the greater the amplitude. |

What type of waves have crests/troughs? | transverse waves |

What type of waves have compressions and rarefactions? | longitudinal waves |

Sound waves compress and stretch the medium they travel through. This must mean sound waves are considered ______ waves. | longitudinal |

The epicenter of an earthquake is where the disturbance in the earth occurs. What direction do the waves of energy travel from the epicenter? | outward in all directions. |

What is the mathematical formula to calculate work? | work = force x distance |

What is the mathematical formula to calculate power? | power = work / timer or power = (force x distance )/time |

What unit is force measured in when calculating work? | Newtons |

What unit is distance measured in when calculating work? | meters |

What unit is work measured in? | Joules or Newton-meters |

What unit is time measured in when calculating power? | seconds |

What unit is used to measure power? | Watts or Joules/sec |

If Jessica used 150 Newtons to carry her bookbag and she 800 meters home, how much work did she do on the bookbag? | w = f x d w = 150 x 800 w = 120,000 joules |

If Parker weighs 80 kg, what is the force he uses to move? 9.81 m/s2 is the force of gravity. | 80 kg x 9.81 = 784.8 Newtons |

If Parker is 784.8 Newtons and he runs 400 meters on the track in 1 minute and 22 seconds, how much work does he do? | w = f x d w = 784.8 x 400 w = 313,920 joules |

If Parker is 784.4 Newtons and he runs 400 meters on the track in 1 minute and 22 seconds, how much power does he use? | time needs to be in seconds.... 1 minute = 60 seconds + 22 seconds = 82 seconds w = 313,920 joules P= w / t P= 313,920 /82 P = 3,828.3 Watts |

Julie and Josh are both 392 Newtons. They both ran around the track two times (800 meters). Julie finished her two laps in 3 minutes and 2 seconds, while Josh took 4 minutes to finish his laps. Who did more work? | They both completed the same amount of work. Time does not affect work. w = f x d, they both require the same amount of force to move around the track and they both traveled the same distance, so they both completed 313,600 joules of work. |

Dominic tried as hard as he could to lift the 225 kg barbell, but it wouldn't budge. How much work did he do? | None, the barbell did not move. w = f x d d= 0 and anything times 0 gives you 0. |