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# THE MCAT-PHYSICS 1

### KINEMATICS

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

GIGA | 10^9 |

MEGA | 10^6 |

KILO | 10^3 |

CENTI | 10^-2 |

MILLI | 10^-3 |

MICRO | 10^-6 |

NANO | 10^-9 |

PICO | 10^-12 |

What should the resultant vector always be? | head-to-head / tail-to-tail |

vector times vector = vector | V=V1V2sintheta |

vector times vector = scalar | V=V1V2costheta |

Does instantaneous velocity = instantaneous speed? | YES |

Does average velocity = average speed? | NO (avg. velocity must be less) |

What creates acceleration? | any change in velocity or direction |

When there is constant "a", what else is there? | Constant force |

When there is no air resistance, what is the only force acting? | gravitational |

What is the ONLY force acting in projectile motion? | gravity (only vertical motion changes) |

Projectile: forces acting in horizontal/vertical | no / yes |

Projectile: "a" in horizontal/ vertical motion? | no / yes (a = 9.8 m/s^2) |

Projectile: velocity component in horizontal / vertical motion? | constant / changing (by 9.8 m/s every second) |

Why does horizontal velocity stay constant? | force not required to keep object in motion (an object in motion stays in motion) force only required to maintain "a" |

What does "a" mean for a projectile? | vertical velocity changes 9.8 m/s every second |

WHy does projectile continue to fall? | inertia |

Drop or throw horizontally, which lands first? | Same time |

What dictates flight time for projectile? | vertical velocity |

Path of projectile NOT experiencing air resistance is independent of what? | mass of projectile |

In Vacuum, do bowling ball and ping pong ball have same path if initial velocities are the same? Do they fall at same rate? | both: yes! |

Why is "a" constant | no air resistance so force (weight) and mass are constant |

What happens with "a" with air resistance? | "a" decreases until it reaches 0 at terminal velocity --> at terminal velocity, weight = friction, so net force = 0, a = 0 note how this differs from constant "a" with no air resistance |

Drop time trick | drop time doubles, drop distance quadruples 1-5 2-20 4-80 |

Ratio of range: height for 30 degrees | 6.7 |

Ratio of range: height for 45 degrees | 4.0 |

Ratio of range: height for 60 degrees | 2.4 |

Shortcut time to the top equation | Voy/g (general) |

Shortcut height at the top equation | Voy^2/2g (general) |

Shortcut range equation | r=Vo^2sin2theta / g (initial and final heights must be the same) |

Max height | 90 degrees (h) |

Maximum range (height too) | 45 degrees (2h) / h/2 |

square root (3) / 2 | 0.86 |

square root (2) / 2 | 0.71 |

1/2 // square root (3) / 2 | 0.58 |

square root (3) / 2 // 0.50 | 1.73 |

When is object decelerating? | velocity is opposite to acceleration |

What does terminal velocity mean? | Velocity is at its final value and won't change for the rest of the time |

What is "a" for an object at terminal velocity? | 0 (air resistance = weight) |

For an object experiencing air resistance in free fall, does acceleration or velocity decrease? | acceleration! |

What effect does air resistance have on flight of ball launched horizontally? | ball travels less distance / in flight for longer / experiences downward "a" that is less than "g" |

What effect does air resistance have on flight of kicked football? | range decreases / flight stays the same (ball reaches peak in shorter time but takes longer to come down than to go up --> cancels out) |

How are force and "a" vectors related? | "a" is always in direction of resultant force |

What two degrees create the same range? | 30 and 60 |

Ball shot at 30, 45, 60 degrees, which lands first? | 30 degrees |

Falling time is identical when _____ and ____ are the same. | starting height and vertical speed |

Speed is magnitude of total velocity and includes both ____. | horizontal and velocity components |

T / F: 2 spheres dropped from same height will have same final velocity no matter what. | TRUE |

T / F: 2 spheres dropped from same height will have same time no matter what | FALSE --> depends on whether inclined plane or not |

Terminal velocity is also? | constant velocity |

Formula for terminal velocity? | v = sqrt(2gh) |

Find average velocity? | vavg = Vf + Vo / 2 |

3 major kinematic equations? | Vf = Vo + at Vf^2 = Vo^2 + 2ax y = Vot +1/2at^2 |

How to find the range? | d = horizontal velocity * time for entire flight |

larger range = _____ height | shorter |

shorter range = ______ height | higher |

At the apex, is the speed or velocity = 0? | NEITHER --> only y component of velocity = 0 |

Why do objects that fall from the same height have the same final velocity even with different launch angles? | same potential energy --> KE transformation |