Card Set Information

2011-02-27 17:00:47
APS test

Show Answers:

  1. Who was the first scientist?
  2. Standard unit of mass and abbreviation

    How is weight measured

    Scientific unit of force
    Kilogram kg.

    Weight in pounds.

    newton, N
  3. Volume
    is how much three-dimensional space a substance (solid, liquid, gas, or plasma) or shape occupies or contains
  4. One kilogram is the same as..
    • 9.8 N
  5. Force = net force

    -vector quanitity
    Vector quantity has both direction and magnitude (how much).

    Arrow that represents direction and length
  6. Does an object at 0 net force mean it is at rest?
    No. It does mean its state of motion remains unchanged. It can be at rest or moving uniformly in a straight line.
  7. When the net force on something is 0, we say the object is in
    mechanical equilibirum
  8. EF=0 means
    • E "the vector sum of"
    • F forces

    The forces acting upward on the body must be balanced by other forces acting downward to make vector sum equal zero.
  9. What is a support force?
    How much is my support force
    • an upward force opposite to the force of gravity.
    • 140 as proven by the scale
  10. Static equillibrium
    Dynamic equillibrium
    • static: at rest
    • dynamic: moving at constant speed in a straight-line path
  11. How can an item be moving at a constant rate and have no net force?
    Once in motion, if there is no net force to change the state of motion, it moves at an unchanging speed and is in dynamic equilibrium. Whether equillibirum is static or dynamic, it equals zero.
  12. Air resistance acts sideways/downward/upward/all directions
  13. Speed
    instantenous: at that given moment
    avg: avg speed for that trip
    distance covered per amount of time traveled.

    The time it takes to move that distance.
  14. When we know both the ___, and the ____, then we know the velocity.
    speed and direction
  15. Acceleration
    undergoing variations in their motion
  16. When a car is turning, even if its speed does not change, it is accelerating...why?
    It's direction is changing.

    Acceleration can involve a change in speed, direction, or both.
  17. Free Fall
    • When the only force that acts on a falling object is that due to gravity.
    • Air resistance does NOT affect motion. In a vaccuum. Falls at a speed of 10 m/s.
  18. Newton's first law of motion
    • Every object continues in a state of rest or of uniform speed in a straight line unless acted on by a nonzero force.
    • Keyword: continues
  19. Newton's second law of motion
    The acceleration produced by a net force on an object is directly proportional to the net force, is in the same direction as the net force, and is inversely porportional to the mass of the object.
  20. Why dont two bricks fall twice as fast?
    Accelerations depeneds not only on the force but on the object's resistance to motion--it's inertia.