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# speeding up revision

### physics speeding up revision made from nzqa questions- ncea level1?

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

In the first three seconds Mary’s acceleration is constant. Use the slope of the graph to calculate its size in meters per second squared. | Slope of graph gives acceleration. Hence: a = 30ms-1/3s = 10 ms-2 |

to find time you? | distance/speed |

to find speed you? | distance/time |

to find distance you? | time x speed |

Using Newton’s Second Law, explain why the sky diver must have no net force acting on her when she is falling at a constant velocity? | The net force on her is zero Newtons at her constant terminal velocity because she has no net acceleration. Hence by Newton’s second law, if anet = 0, then Fnet = m anet = 0 N. |

Mary has a mass of 65 kg. Calculate the size of the force of gravity acting on her as she falls. | F = mg = 65kg x 10 N/kg = 650 N |

terminal velocity | -drag and weight balanced -no accelerations; a=0 -at fastest possible speed -constant speed -zero change in speed, zero slope, zero acceleration -F=m,a. if a=0 f=0; weight less |

at slope= | ------- as constant acceleration |

vt slope= | acceleration/changing speed; no slope no acceleration= constant speed |

dt slope= | speed/velocity, more slope speed; no slope no acceleration = constant speed |