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# PHYS 172 Final

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

True/False: The rate of change of momentum is always tangent to the path | False |

True/False: The momentum of an object always point in the same direction as its velocity. | True |

True/False: In general, the total momentum of a physical system can change with time. | True |

True/False: A heavier object attracts a lighter object with larger gravitational force than the lighter object attracts the heavier one | False |

True/False: Momentum is always perpendicular to net force. | False |

True/False: The period of oscillations is independent of amplitude. | True |

Is the mass of a hydrogen atom smaller, larger, or equal to the sum of the proton mass and the electron mass | Smaller |

Position update formula | Rf=Ri+Vavg(Tf-Ti) |

What are the four fundamental forces? | Gravity, electromagnetic, strong, and weak force |

When is linear momentum conserved? | When the system is isolated; when Fnet is 0 (external forces cancel) |

Total stretch of two spring in series? | 2s |

Total stretch of two springs in parallel | s/2 |

Frequency equation | 1/T |

A change in what results in a parallel force only (perpendicular force =0)? | magnitude of momentum |

A change in what results in a perpendicular force only (parallel force =0)? | direction of momentum |

What type of force exist on an object moving in a circle? | perpendicular |

Work is positive when delta(r) and F are in the _________ direction. | same |

The change in potential energy (delta U) is equal to... | -W |

K(planet)+U(sys) = | constant |

K+U<0 Bound or unbound? | Bound |

K+U>=0 Bound or unbound? | unbound |

True or false? If object does not move, work can be done | False |

Work equation | F.d Fdcos(theta) |

True or false? In a round trip the potential energy does not change | True |

Collisions at the __________of a falling object impart more impulse than collisions at the _________ of the falling object. | bottom; top |

Adding a photon ________ the energy of the atom | increases |

Center of mass equation | (m1r1+m2r2+m3r3...)/(m1+m2+m3...) |

Angular momentum equation (L=?) | L=rxp L=rpsin(theta) |

Torque equation | T=rxF T=rFsin(theta) |

For two vectors along the same line, the torque is equal to | 0 |

What is the fundamental assumption of statistical mechanics? | Each microstate corresponding to a given macrostate is equally probable |

True or false? For a monoatomic gas there is rotational but not vibrational energy | False; There is no rotational or vibrational |

What is the formula for Evib and Erot for a diatomic gas | kT |

For Esys = 0, is K = -U? Why or why not? | No, because delta(K) = -delta(U) |

For curved motion of people in a car, what is the direction of the net force acting on the people as the car is turning? | Towards the center of the 'circle' |

In a ferris wheel at constant velocity, is the magnitude of net force constant? What about the direction? | Magnitude is constant, (Fperp. = mv^2/R) Direction is not constant because always pointing towards center of motion |

In an inelastic collision, which will experience a larger change in velocity, an object of large or small mass? | Small |

In an inelastic collision, which will experience a larger change in momentum, and object of large or small mass? | The change in momentum is equal because of the law of conservation of momentum |

Positive or negative? 1. The work done by the engine on an accelerating car. 2. The work done by the brakes on a decelerating car. | 1. Positive 2. Negative |

How can you determine the work done by the Earth on the moon? | 0 because of the circular path, force is only perpendicular and therefor the angle is 90deg. w=F(deltaR)cos(theta)... cos(90)=0 |

Positive or negative sign of work? 1. A spring being stretched. 2. A spring being compressed | 1. negative 2. negative *Work done by a spring will always be negative unless it is at equilibrium, at which point the work is 0 |

For an oscillating O2 molecule, how does the mass of the molecule compare to the total mass of 2 non interacting oxygen atoms? | The mass of the O2 molecule is smaller |

Two identical balls go down a hill, Ball 1 slides and Ball 2 rolls. 1. Which will have a larger Ktotal? 2. Which will have a larger Ktrans? 3. Which will have a larger Krot? 4. Which will get down first? | 1. They will have the same Ktot 2. Ball 1 will have a greater Ktrans 3. Ball 2 will have a greater Krot 4. Ball 1 will get down first |

When you add a block of something at a temperature to a bucket of water at another temperature, what form of the energy principle allows you to solve for the final temperature, specific heat of the block, etc. | E(water)+E(block) = 0 *use E=mc(deltaT) |

Vector subtraction: For vector C = vector A - vector B, vector C goes from the _____ of vector ___ to the ____ of vector ____ | Tip of A to tip of B |

In a spring-mass system, what does the energy principle tell you? | Uspring + Kmass = constant... so Uspring(f)+Uspring(i) = Kmass(f) + Kmass(i) |

What is the fundamental assumption of statistical mechanics? | Every microstate is equally probable |

Mass of a proton | 1.67e-27 |

If you are on a rollercoaster, what must be true of the forces for you to feel weightless? How would you determine the speed at this point | The force from the seat must be zero so the only force working on you is mg. To solve for speed, mg=mv^2/r |

Each Einstein model is represented by ____ one-dimensional oscillator(s). | 3 |

For a chain in a pile being straightened, what is the distance of the point particle system | d(cm) = d-1/2 |