**physics Grade 11 Exam

Front 1

Define: Vector quantity

Back 1

A quantity that has both magnitude and direction

Front 2

Define: kinematics

Back 2

The study of motion

Front 3

What is this symbol?

Back 3

Average speed

Front 4

The equation for average speed

Back 4

d is the distance travelled in total time.

Average speed is the total distance travelled divided by the total time of travel. (The symbol for average speed, vav , is taken from the word “velocity.”) The equation for average speed is

where d is the total distance travelled in a total time t.

Hint 4

Front 5

Define instantaneous speed

Back 5

The speed at a particular instance

Front 6

Average velocity

Back 6

Front 7

Scalar quantity

Back 7

Speed, distance, and time are examples of a scalar quantity, a quantity that has magnitude (or size) only, but no direction.

Front 8

Summary - Uniform Motion

Back 8

Key Points

A vector quantity has both magnitude and direction. Examples areposition, displacement, and velocity.• Position, d , is the distance and direction of an object from a referencepoint. Displacement, d, is the change in position of an object from areference point.• Average velocity is the ratio of the displacement to the time interval,or v av dt.• The straight line on a position-time graph indicates uniform motion andthe slope of the line represents the average velocity between any two times.• The area under a line on a velocity-time graph represents the displacementbetween any two times.

Front 9

Position

Back 9

A common vector quantity is position, which is the distance and direction of an object from a reference point. For example, the position of a friend in your class could be at a distance of 2.2 m and in the west direction relative to your desk. The symbol for this position is = 2.2 m [W].

Front 10

Displacement

Back 10

Another vector quantity is displacement, which is the change in position of an object in a given direction.

Hint 10

Front 11

Variables that can be measured directly

Back 11

variables that can be measured directly are usually time and either position or displacement. The third variable, velocity, is often obtained by calculation.

Front 12

Velocity time graph

Back 12

velocity-time graph can be used to find the displacement during various time intervals.

Front 13

Average velocity in two dimensions

Back 13

Average Velocity in Two Dimensions

Just as for one-dimensional motion, the average velocity for two-dimensional motion is the ratio of the displacement to the elapsed time. Since more than one displacement may be involved, the average velocity is described using the resultant displacement.

Front 14

Relative velocity

Back 14

The velocity of a body relative to a particular frame of reference is called relative velocity.

Hint 14

Front 15

Acceleration

Back 15

Calculating Acceleration

Acceleration is defined as the rate of change of velocity. Since velocity is a vector quantity, acceleration is also a vector quantity. The instantaneous acceleration is the acceleration at a particular instant. For uniformly accelerated motion, the instantaneous acceleration has the same value as the average acceleration. The average acceleration of an object is found using the equation

Hint 15

Front 16

Average acceleration

Back 16

Back (Definition)

Front 17

What is the process of deriving equations?

What are the three main stages:

Back 17

1. State the given facts and equations.

2. Substitute for the variable to be eliminated.

3. Simplify the equation to a convenient form.

Front 18

What is the average velocity for two-dimensional motion

Back 18

It is the ratio of the displacement to the elapsed time.

Hint 18

Front 19

Frame of Reference

Back 19

coordinate system relative to which a motion can be observed

Hint 19

Any motion observed depends on the frame of reference chosen.

Front 20

Summary - Two dimensional Motion

Back 20

Front 21

What is accelerated motion

Back 21

nonuniform motion that involves change in an object’s speed or direction or both

Hint 21

If an object is changing it's speed in a non-uniform fashion, its acceleration is non-uniform.

Front 22

uniformly accelerated motion

Back 22

motion that occurs when an object travelling in a straight line changes its speed uniformly with time

Hint 22

Also occurs when an object travelling in a straight line slows down uniformly.

Front 23

Define: instantaneous velocity

Back 23

velocity that occurs at a particular instant

Front 24

Define: Tangent

Back 24

A straight line that touches a curve at a single point and has the same slope as the curve at that point

Front 25

What is Tangent Technique

Back 25

A method of determining velocity on a position-time graph by drawing a line tangent to the curve and calculating the slope

Front 26

instantaneous velocity

Back 26

velocity that occurs at a particular instant

Front 27

Summary Uniform Acceleration

Back 27

Front 28

Acceleration due to gravity

Back 28

The vector quantity 9.8 m/s2 [down], or 9.8 m/s2 [↓], occurs so frequently inthe study of motion that from now on, we will give it the symbol g , which represents the acceleration due to gravity

Hint 28

(Do not confuse this g with the g used as the symbol for “gram.”)

Front 29

Back 29

Summary card of Acceleration

Front 30

terminal speed:

Back 30

maximum speed of a falling object at which point the speed remains constant and there is no further acceleration

Front 31

derived unit:

Back 31

unit that can be stated in terms of the seven base units

Front 32

base unit:

Back 32

Unit from which other units are derived or made up

Front 33

resultant displacement

Back 33

vector sum of the individual displacements

Hint 33

Front 34

Force

Back 34

a push or a pull

Front 35

What are the fundamental forces?

Back 35

Forces are classified into four categories—gravitational, electromagnetic, strong nuclear, and weak nuclear

Front 36

gravitational force or force of gravity:

Back 36

force of attraction between all objects

Front 37

Electromagnetic force

Back 37

force caused by electric charges

Front 38

strong nuclear force

Back 38

Force that holds protons and neutrons together in the nucleus of an atom

Hint 38

The strong nuclear force holds the protons and neutrons together, even though the protons are influenced by the electric force of repulsion. This nuclear force is a short-range force but is much stronger than the electromagnetic force. It is significant only when the particles are close together

Front 39

weak nuclear force:

Back 39

force responsible for interactions involving elementary particles such as protons and neutrons

Hint 39

This type of force is noticed only at extremely small distances.

Front 40

Normal force:

Back 40

Force perpendicular to the surfaces of the objects in contact

Front 41

Friction

Back 41

Force between objects in contact and parallel to contact surfaces

Front 42

Tension:

Back 42

Force exerted by string, ropes, fibres, and cables

Front 43

Newton

Back 43

newton: (N) the SI unit of force

Hint 43

The newton is a derived SI unit, which means that it can be expressed as acombination of the base units of metres, kilograms, and seconds. For theremainder of your study of forces and motion, it is important that you performcalculations to express distance in metres, mass in kilograms, and time in seconds. In other words, all units must conform to the preferred SI units of metres,kilograms, and seconds.

Front 44

system diagram:

Back 44

sketch of all the objects involved in a situation

Front 45

free-body diagram:

Back 45

(FBD) drawing in which only the object being analyzed is drawn, with arrows showing all the forces acting on the object

Front 46

Forces in Nature

Back 46

Front 47

Dynamics

Back 47

the study of the causes of motion

Front 48

Inertia:

Back 48

the property of matter that causes a body to resist changes in its state of motion

Hint 48

The amount of inertia an object possesses depends directly on its mass: the greater the mass, the greater the inertia the body possesses

Front 49

first law of motion:

Back 49

if the net force acting on an object is zero, the object will maintain its state of rest or constant velocity

Hint 49

Summarize - Newton’s first law of motion by stating four important results of it:

(a) Objects at rest tend to remain at rest.

(b) Objects in motion tend to remain in motion.

(c) If the velocity of an object is constant, the net external force acting on it must be zero.

(d) If the velocity of an object is changing in either magnitude or direction or both, the change must be caused by a net external force acting on the object. This fact sets the stage for experimentation in dynamics

Front 50

Summary - Newton's First Law of Motion

Back 50

Galileo’s real and virtual experiments led the way for Newton to formulate his three laws of motion.

• The net force acting on an object, Fnet, is the vector sum of all the forces acting on the object.

• Newton’s first law of motion, often called the law of inertia, states that ifthe net force acting on an object is zero, the object will maintain its state ofrest or uniform velocity.

• The first law of motion is observed and applied in many situations,including the need for restraint systems in automobiles.

Front 51

Second law of motion:

Back 51

if the net external force on an object is not zero, the object accelerates in the direction of the net force, with magnitude of acceleration proportional to the magnitude of the net force and inversely proportional to the object’s mass

Front 52

Equations - 2nd Law of Motion

Back 52

Front 53

Summary - Second Law of Motion

Back 53

Newton’s second law of motion relates the acceleration of an object to the mass of the object and the net force acting on it. The equation is

a = F net/m or F net = ma .

• Newton’s second law is applied in many problem-solving situations.

Front 54

Third law of motion:

Back 54

For every action force, there is a reaction force equal in Third Law of Motion magnitude, but opposite in direction

Hint 54

Newton’s third law of motion, which always involves two objects, states that for every action force, there is a reaction force equal in magnitude, but opposite in direction.

• Action-reaction pairs of forces are applied in many situations, such as a person walking, a car accelerating, and a rocket blasting off into space.

Front 55

Force Field

Back 55

space surrounding an object in which the object exerts a force on other objects placed in the space

Front 56

gravitational field strength:

Back 56

the amount of force per unit mass acting on objects in the gravitational field

Front 57

mass:

Back 57

the quantity of matter in an object

Front 58

weight:

Back 58

the force of gravity on an object

Front 59

Gravitational Force on Earth’s Surface

Back 59

Earth’s gravitational field is the space surrounding Earth in which the forceof gravity has an effect.• On Earth’s surface, the average gravitational field strength isg = 9.8 N/kg [↓].• Mass is the quantity of matter (measured in kilograms) and weight is theforce of gravity (measured in newtons and determined using the equationFg= mg ).• The magnitude of g decreases as the distance from Earth’s centre increases,so this magnitude is smaller at higher altitudes, and it is greater at the polesthan at the equator because Earth is slightly flattened at the poles.• An object orbiting another object maintains its orbit by constantly free falling toward the central body. For example, the International Space Station and its contents constantly free fall toward Earth.

Front 60

Law of universal gravitation:

Back 60

The force of gravitational attraction between any two objects is directly proportional to the product of the masses of the objects, and inversely proportional to the square of the distance between their centres.

Front 61

Symbols - law of universal gravitation

Back 61

FGis the force of gravitational attraction between any two objects.m1 is the mass of one object.m2 is the mass of a second object.d is the distance between the centres of the two objects.(Objects are assumed to be spherical.)

Front 62

Equation: Law of universal gravitation

Back 62

Front 63

5(a) For an object undergoing free fall, the weight, Fg, is the force which causes the object to accelerate downward.

(b) When an object rests on a horizontal surface, the object’s weight causes a downward force on the surface. This force is balanced by an upward force of the surface, the normal force, on the object.

(c) The upward force required to raise an object at a constant speed is equal in magnitude to the object’s weight.

Back 63

Front 64

Static friction:

Back 64

The force that tends to prevent a stationary object from starting to move

Front 65

Starting friction:

Back 65

The amount of force that must be overcome to start a stationary object moving

Front 66

kinetic friction:

Back 66

The force that acts against an object’s motion in a direction opposite to the direction of motion

Front 67

What is a bearing

Back 67

A bearing is a device containing many rollers or balls that reduce friction while supporting a load (Figure 3). Bearings change sliding friction into rolling friction, reducing friction by up to 100 times.

Front 68

Summary - The Effects of Friction

Back 68

Friction acts parallel to 2 surfaces in contact in a direction opposite to the motion or attempted motion of an object.

Static friction tends to prevent a stationary object from starting to move

Kinetic friction acts against an object's motion; it is usually less than static friction

Fro an object to maintain uniform velocity, the net force acting on it must be zero, so for an object moving at uniform velocity on a horizontal surface, the applied horizontal force must be equal in magnitude to the kinetic friction.

Unwanted friction can be reduced by changing sliding to rolling, by using bearings and by using lubrication.

The extent to which certain factors affect friction, such as the types of surfaces in contact or the mass of the object, can be determined using a controlled experiment.

Front 69

Coefficient of friction:

Back 69

Ratio of the magnitude of friction to the magnitude of the normal force

Hint 69

The coefficient of friction is a number that indicates the ratio of the magnitude of the force of friction, Ff, between two surfaces to the magnitude of the force perpendicular to these surfaces. Recall that the magnitude of the force perpendicular to the surface is called the normal force, FN, so the coefficient of friction is the ratio of Ff to FN.

Front 70

Equation - coefficient of friction

Back 70

Front 71

Coefficent of Kinetic friction

Back 71

The coefficient of kinetic friction is the ratio of the magnitude of the kinetic friction to the magnitude of the normal force.

Hint 71

Front 72

The coefficient of static friction

Back 72

is the ratio of the magnitude of the maximum static friction to the magnitude of the normal force.

Hint 72

Front 73

Summary - Analyzing Motion with Friction

Back 73

The coefficient of friction, m, is the ratio of the magnitude of the force of friction to the magnitude of the normal force between two surfaces in contact

• These coefficients can be determined using a controlled experiment in which a horizontal applied force is used to move an object with constant velocity across a horizontal surface.

Problem-solving skills developed throughout this unit can be synthesized in order to solve problems that include friction and coefficients of friction.

Front 74

Energy:

Back 74

The capacity to do work

Front 75

Heat:

Back 75

the transfer of energy from a warmer body or region to a cooler one

Front 76

Forms of Energy

Back 76

Thermal

Electrical

Radiant

Nuclear potential

Gravitational Potential

Kinetic

Elastic potential

Sound

Chemical Potential

Front 77

thermal energy

Back 77

The atoms and molecules of a substance possess thermal energy. The more rapid the motion of the atoms and molecules, the greater the total thermal energy

Hint 77

Thermal energy in the boiling water transfers tothe pasta to cook it.

Front 78

electrical

Back 78

This form of energy is possessed by charged particles. The charges can transfer energy as they move through an electric circuit.

Hint 78

Electrical energy delivered to the stoveheats the water in the pot

Front 79

Radiant

Back 79

Radiant energy travels by means of waves without requiring particles of matter.

Hint 79

The Sun emits radiant energies, such as infrared radiation, visible light, and ultraviolet radiation. The Sun’s energy comes from nuclear fusion reactions in its core

Front 80

Nuclear Potential

Back 80

The nucleus of every atom has stored energy. This energy can be released by nuclear reactions such as nuclear fission and nuclear fusion.

Hint 80

The Sun emits radiant energies, such as infrared radiation, visible light, and ultraviolet radiation.

The Sun’s energy comes from nuclear fusion reactions in its core

Front 81

Gravitational Potential

Back 81

A raised object has stored energy due to its position above some reference level.

Hint 81

At the highest position above the trampoline, this athlete has the greatest amountof gravitational potential energy. Theenergy changes to kinetic energy as herdownward velocity increases. The kineticenergy then changes into elastic potential energy in the trampoline to help herbounce back up.

Front 82

kinetic

Back 82

Every moving object has energy of motion, or kinetic energy.

Hint 82

At the highest position above the trampoline, this athlete has the greatest amountof gravitational potential energy. The energy changes to kinetic energy as herdownward velocity increases. The kinetic energy then changes into elastic potential energy in the trampoline to help herbounce back up.

Front 83

Elastic potential

Back 83

This potential energy is stored in objects that are stretched or compressed.

Hint 83

At the highest position above the trampoline, this athlete has the greatest amountof gravitational potential energy. The energy changes to kinetic energy as herdownward velocity increases. The kinetic energy then changes into elastic potential energy in the trampoline to help herbounce back up.

Front 84

Sound

Back 84

This form of energy, produced by vibrations, travels by waves through a material to the receiver

Hint 84

Chemical potential energy is released when fireworks explode. Some of that energy is changed into sound energy

Front 85

Chemical potential

Back 85

Atoms join together in various combinations to form many different kinds of molecules, involving various amounts of energy. In chemical reactions, new molecules are formed and energy is released or absorbed.

Hint 85

Chemical potential energy is released when fireworks explode. Some of that energy is changed into sound energy

Front 86

Energy transformation:

Back 86

the change from one form of energy to another

Hint 86

We can summarize these changes using an energy transformation equation.

For the microwave oven example described above, the equation is

electrical energy → radiant energy → thermal energy

Front 87

work:

Back 87

The energy transferred to an object by an applied force over a measured distance

Front 88

Relationships between work & applied force

Back 88

Using the symbols W for work, F for the magnitude of the applied force,and d for the magnitude of the displacement, the relationships among these variables are

Hint 88

Front 89

What is the Newton metre

Back 89

Since force is measured in newtons and displacement is measured in metres, work is measured in newton metres (N•m).

The newton metre is called the joule(J) in honour of James Prescott Joule, an English physicist who studied heat and electrical energy (Figure 2). Since the joule is a derived SI unit, it can be expressed in terms of metres, kilograms, and seconds

Front 90

Examples of Zero Work

Back 90

Zero Work Situations exist in which an object experiences a force, or a displacement, or both, yet no work is done on the object. If you are holding a box on your shoulder, you may be exerting an upward force on the box, but the box is not moving, so the displacement is zero, and the work done on the box, W = Fd, is also zero.In another example, if a puck on an air table is moving, it experiences negligible friction while moving for a certain displacement. The force in the direction of the displacement is zero, so the work done on the puck is also zero. In a third example, consider the force exerted by the figure skater who glides along the ice while holding his partner above his head (Figure 5). There is both a force on the partner and a horizontal displacement. However, the displacement is perpendicular (not parallel) to the force, so no work is done on the woman. Of course, work was done in lifting the woman vertically to the height shown.

Front 91

How is work measured?

Back 91

Work is a scalar quantity measured in joules (J).

Front 92

What is the value when force & displacement are in the same direction?

Back 92

If the force and displacement are in the same direction, the work done by the force,

is a positive value. If the force and displacement are in opposite directions, the work done is a negative value.

Front 93

Position

Back 93

Back (Definition)

Front 94

Describe displacement

Back 94

Back (Definition)

Front 95

Vector scale diagrams

Back 95

They show the vectors associated with a displacement drawn to a particular scale

Front 96

What is a directed line segment?

Back 96

A straight line between two points with a specific direction