Phsyics

• Base of support

  Area bound by outermost regions of contact between a body & support surface(s)
• Balance


  Ability to control equilibrium; an important part of agility; ability to change direction at high speeds
• Stability


  Resistance to disruption of equilibrium; ability of a body to return to its original position (equilibrium) after being diplaced
• Center of gravity


  Point around which mass is evenly distribute and through which the force of gravity acts- Sum to a total of zero
• Center of mass


  Point the entire mass of the body may be assumed to be concentrated
• Axis of rotation


  Point around which something rotates
• Static equilibrium

  There is no state of motion
• Muscle tension & muscle moment arm


  The product of _____ & ______ produces a torque at the joint crossed by the muscle.
• Shorter


  A force can move a resistance through a large range of motion when the force arm is ____ than the resistance arm.
• Longer

  A force can balance a larger resistance when the force arm is ___ than the resistance arm
• Equilibrium


  T=0 Nm
• Mechanical disadvantage


  Muscles in general are at a...
• Mechanical advantage


  Ratio of moment arm of the force (force arm) to the moment arm of the resistance (resistance arm) for a given lever
• Lever


  Simple machine consisting of a relatively rigid barlike body that can be made to rotate about an axis or a fulcrum- 1st, 2nd, & 3rd class
• Moment arm of a force

  Perpendicular distance from the force's line of action to the axis of rotation
• Torque


  Turning effect caused by eccentric force; rotary effect of a force about an axis of rotation(force x moment arm) Units: Nm
• Eccentric forces


  Forces that are not directed through an object's center of massResult in change in linear position AND rotation of object
• Centric forces


  Forces that are directed through an object's center of massResult in a change in linear position
• How did the formulation of the law of universal gravitation affect science?

  The formulation of the law of universal gravitation is one of the major reasons for the success in science that followed, for it provided hope that other phenomena of the world might also be described by equally simple and universal laws.
• What happens to the gravitational field of the a star that has collapsed into a black hole?


  When a massive star collapses into a black hole, there is no change in the gravitational field at any point beyond the original radius of the star.
• What causes ocean tides?

  Newton showed that the ocean tides are caused by differences in the gravitational pull of the moon on opposite sides of Earth.
• What sensation do we interpret as wright?

  Pressure against Earth is the sensation we interpret as weight.
• Describe the gravitational field of Earth at its center.

  The gravitational field of Earth at its center is zero.
• What kind of field surrounds Earth and causes objects to experience gravitational forces?

  Earth ca be thought of as being surrounded by a gravitational field that interacts with objects and causes them to experience gravitational forces.
• How does the force of gravity change with distance?

  Gravity decreases according to the inverse square law. The force of gravity weakens as the square of distance.
• What did Newton discover about gravity?


  Newton discovered that gravity is universal. Everything pulls on everything else in a way that involves only mass and distance.
• What theory of the solar system did Newton's theory of gravity confirm?

  Newton's theory of gravity confirmed the Copernican theory of the solar system.
• Why doesn't the moon hit Earth?

  The moon is actually falling toward Earth but has great enough tangential velocity to avoid hitting Earth.
• What was Newton's reasoning about the apple falling from the tree?

  Newton reasoned that the moon is falling toward Earth for the same reason an apple falls from a tree--they are both pulled by Earth's gravity.
• ocean tide


  Newton showed that the ocean tides are caused by differences in the gravitational pull of the moon on opposite sides of Earth.
• Gravitational field


  A Gravitational field occupies the space surrounding a massive body. A Gravitational field is an example of a force field,for any mass in the field space experiences a force.
• Inverse-square law


  When a quantity varies as the inverse square of its distance from its source, it follows an inverse-square law.
• Universal Gravitational constant


  The universal gravitational constant, G, in the equation for universal gravitation describes the strength of gravity.
• Law of universal gravitation


  Newton's law of universal gravitation states that every object attracts every other object with a force that for any two object is directly proportional to the mass of each object.
• eccentricity of a line

  1
• eccentricity of a circle


  0
• focus of orbit

  
• ellipse


  a flat circle

  
• orbit


  go around (Earth orbits the sun)

  
• axis


  An imaginary line that passes through Earth's center and the North and South poles