Movement Notes

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1. Scaler Quantities are quantities that require magnitude but do not require direction. Scaler Quantities: Distance, Speed, Time, Mass, Temperature, Charge, Density.
Vector Quantities are quantities that require both magnitude and direction. Vector Quantities: Displacement, Velocity, Acceleration, Momentum, Force, Moment, Impulse.

4. Displacement(s): The change in position of a body in a given direction. s = Final Position-Original Position. The standard international unit for Displacement is Metres (m) in a specific direction.

5. A runner runs around a circular track once. Distance=400m Displacement=400-400=Om

6. Speed(v): Is the distance (how far you have gone) traveled in a given amount of time. Its standard international unit is m/s for metres per second.
Velocity(v): Is the displacement (how far you have gone in a certain direction) per time interval. Its standard international unit is m/s for metres per second plus a direction must be included.

7. A car is going at 40m/s. (Scaler/Speed) A car is going at 40m/s north. (Vector/Velocity)

9. The distance between the dots (in m)/(htz/1000)=Velocity. Use dots of each side of dot, add distance and divide by 2 to find average velocity. (#Ticker Tape Timer Practical Page 1 of journal)

10. To do this we use a formula to find the magnitude of velocity. In terms of direction, vectors must be used to represent the formula. In the formula (V-U)/T if the initial velocity was 5m/s north, it would now be 5m/s south.

11. Acceleration: Is the change in velocity per unit of time. It is a vector quantity and must have a direction. Its standard international unit is m/s/s or m/s^2.

12. #Stawa set 20 (pg 62) Remember when drawing vector diagrams to the formula of acceleration, (v-u)/t, remember to put the initial velocity in the opposite direction due to it being subtracted.

13. Acceleration=Mass/Force An acceleration of zero means that a constant force is being applied to a body.

14. See #Ticker Tape Timer Practical Page 1 of journal and class notes. Page 220 of Physics book.

15. Distance/Time Slope=V Velocity/Time Slope=Acceleration Area=Distance Acceleration/Time=Velocity Change

18. Acceleration due to gravity 9.8m/s/s. The resultant of the vectors shows the result even though it is not the path it takes. Horizontal and vertical vectors are independent.

19. Mass is an amount of matter. The standard international unit for the mass of the object is kilograms (Kg)

20. Mass is an amount of matter and weight is the force of gravity felt by a mass. Weight is a measure of the gravitational force acting on an object; direction is down (toward the earth’s center); symbol is W W=mg
Where W is the weight of the object in Newtons, m is the mass of the object in kilograms, and g is the acceleration due to gravity.
You can easily change the weight of an object by moving it to different places where the force of gravity is different but an object is pretty much stuck with how much mass it has. For example if you weigh yourself at earth's north pole and then at the equator you'll find that you lose about 1/2 pound at the equator because the force of gravity is different there. The amount of stuff that you're made of, your mass, stays the same however.
Suppose that you're feeling a little overweight and decide to do something about it. Knowing that astronauts on the moon weigh only 1/6 of what they do on earth you book a ticket on the next moon mission in the hopes of losing weight when you get there. When you arrive you will weigh less. You'll weigh a lot less. But you will be at least a little disappointed because you will not have lost any mass. Your physical appearance will be the same because you're still made of the same amount of stuff that you were when you left earth. You only weigh less because the moon is pulling on you with less force.
Weight is a measure of the gravitational force acting on an object; direction is down (toward the earth’s center); symbol is W W = m g Where W is the weight of the object in Newtons.

21. Forces cause an attraction or repulsion between two objects. You can't see the force but rather its effects. You cant see gravity but you can see the apple falling to the ground.

22. Momentum is a function of an objects mass as well as its velocity. Momentum is a measure of how hard it is to stop a moving object; it is the product of the object's mass and its velocity; it is a vector quantity; symbol is p and SI units are either N sec or kg m/sec. p=mv
where p is momentum, m is mass in kg, and v is velocity in m/s.
High mass objects can have low momentum when they have low velocities; low mass objects can have high momentum when they have high velocities. The greater the momentum of an object, the greater the effect it will have on an object into which it impacts.

23. #Stawa Set 24 (pg 74)
Newton’s Laws of Motion:
1. Newton’s First Law: an object in motion remains in motion at constant speed and moving in a straight line and an object at rest remains at rest unless acted upon by an outside force; called the law of inertia
Equilibrium: an object is in equilibrium when its velocity is zero or its velocity is constant.
Inertia: a measure of how an object resists changes in motion; it is a measure of an object’s mass
2. Newton’s Second Law: An unbalanced force (or net force) causes an object to accelerate; this acceleration is directly proportional to the unbalanced force and inversely proportional to the object’s mass; called the law of acceleration a = F / m or F = m a
Equilibrium: an object is in equilibrium when no unbalanced force (or net force) acts on it
3. Newton’s Third Law: When one object exerts a force on another object, the second object exerts a force on the first object that is equal in magnitude, but opposite in direction; for every action, there is an equal, but opposite reaction; called the law of action-reaction

24. Newton’s First Law: an object in motion remains in motion at constant speed and moving in a straight line and an object at rest remains at rest unless acted upon by an outside force; called the law of inertia. A body's inertia increases as its roughness changes.

25. Force push or a pull; symbol is F; SI unit is the Newton, or N One Newton is the force necessary to cause a one kilogram mass to accelerate at the rate of 1 m/s^2 1N = 1kg m/s^2. An object is moving as a force is being applied to it.

26. Impulse is a force exerted over a time interval; symbol is J and SI units are either N sec or kg m/sec. J=Ft where J is impulse, F is force, and t is time in seconds. This is equal to its change in momentum.

27. According to Newton's second law, an unbalanced force causes a mass to accelerate. Restating Newton's second law in terms of momentum, an impulse causes the velocity of an object with mass to change, therefore causing a change in momentum J=Ft=mDv=Dp where D stands for "change in"

28. Law of conservation of momentum: the momentum of a closed, isolated system is constant; the sum of the initial momentum of the objects is equal to the sum of the final momentum of the objects Spi=Spf where pi is the initial momentum and pf is the final momentum. Objects transfer their momentum in collisions. The total momentum before the collision is equal to the total momentum after the collision in a closed, isolated system. If one object loses momentum in a collision, then another object must gain that amount of momentum. (Body 1)MU+(Body 2)MU=(Body 1)MV+(Body 2)MV The Initial Velocity of the first object times by its mass plus the Initial Velocity of the second object times by its mass equals the Velocity of the first object times by its mass plus the Velocity of the second object times by its mass.

31. For every action force there is an equal and opposite reaction force. F(A on B)=-F(B on A) Whenever a force acts against a fixed surface, the surface provides a normal force that is at right angles to the surface. The size of the normal force depends on the orientation of the surface to the force. A rocket accelerates gas from its engines producing a downwards force. The earth produces an upwards force that is equal to the action force.

33. Free body diagrams show all the forces acting on an object. eg air resistance, gravity, normal force. If the body has a constant velocity, its sum of all forces equal zero.

34.
Light Energy (Sun, Artificial Light)
Heat Energy (Sun, Friction, Flame)
Sound Energy (Vibration Sources)
Magnetic Energy (Magnetic Materials)
Chemical Energy (Chemical Bonds)
Electrical Energy (Movement of Electrons)
Solar Energy (Sun)
Nuclear Energy (Nucleus of atom)
Kinetic Energy (Moving Object)
Geothermal Energy (Heat in Earth)
Potential Energy (Relative position of object to ground.)

35. When a force moves it point of application, work is done. This is expressed mathematically by w=fs. A force moves it point of application when the velocity of the body, parallel to the force, is not equal to zero .

36. Work is done in physics when a force is applied on an object and there is a displacement parallel to the direction of the force. No work is done unless there is a displacement parallel to the direction of the force. The force doing the work could be a component of the applied force. It would be the component parallel to the displacement.
The general form of the work equation is: W=Fs where W is the work, F is the force acting in the direction of the displacement, s.
Here is an example of a situation where a force is applied and no work is done: A man holds a 50 N weight. No work is done (even though he must exert a force to hold the weight) because there is no displacement parallel to the direction of the weight.
Here is an example of a situation where there is a force applied and there is displacement and no work is done against the object's weight: A man walks around the room holding a 50 N weight. The object's weight acts down. For work to be done against the weight there has to be displacement in the direction of the weight (either up or down). There is none so no work is done against the weight. There is work done against friction as the man walks around the room.

38. Energy is the ability to do work (this definition does not describe all kinds of energy, but will be sufficient for our study of mechanical energy.)
Work and energy are interrelated. If you do work, you do something as a result of your efforts. If work is done on a particle, its speed is changed. We relate the motion of the particle to the work done using a property called kinetic energy. It takes work to make an object move and a moving object can do work.

39. A system that has energy can have its energy transferred to another object or transformed to another form of energy. If the transferring of energy creates movement, work is done.

40. The Joule is the SI unit of work. 1J=1Nm, or one Joule equals one Newton metre.

41. Law of Conservation of Energy: energy can be transformed from one form to another in an isolated system, but it cannot be created or destroyed. The total energy of the system is constant.

42. Energy can be transformed from one type to another. The sum of the energy stays constant in a isolated system.

43. In a car, the chemical energy can be transformed to sound, kinetic and heat energies.

45. Kinetic energy :energy due to the motion of an object; if an object has a velocity, it has kinetic energy. KE=1/2m(v^2) where m is mass in kilograms and v is the objects speed
If an object's mass is doubled, its kinetic energy is doubled, but if its speed is doubled, its kinetic energy is increased greater as it is a squared number!

47. An Elastic collision is defined as a collision where kinetic energy and momentum of the system are both conserved. An Inelastic collision is defined as a collision where the momentum is conserved but the kinetic energy is transformed into other forms of energy.

48. Potential energy (usually U but I use PE) energy due to an object's position.
Gravitational potential energy: energy of an object due to its position in a gravitational field PE=mgh where m is mass in kilograms, g is the acceleration due to gravity, and h is the object's height. (Thus, mg is equivalent to the object's weight.)

49. Any body that is above the ground has potential energy. Pen on a desk, Bungie jumper.

51. Principle of Conservation of Mechanical Energy: the total mechanical energy of an object remains constant as an object moves provided that no work is done by forces other than gravity. Etot=KE+PE At the top of the cliff, Potential energy is equal to 200J.Half way down the cliff, the Kinetic energy is equal to 100J, the Potential energy is equal to 100J. At the bottom of the cliff, the Kinetic energy is equal to 200J.

53. Power is the rate of doing work. P = W/t where P is the power dissipated, W is the work done, and t is time in seconds.

56. Efficiency is the percentage of energy which is transformed to a useful form by a device known as the efficiency of that device. All practical energy transformations lose some energy as heat.
Efficiency=Useful Output/Total Input*100=useful energy transferred*100/total energy supplied

Created : 28 October 2000
Last modified : 26 November 2000
Author : Chad Silver email:Chaddysi@start.com.au
Site maintained by : Chad Silver