SAGS Definitions - Physics

Question 1

Define a vector and give examples

Answer 1

a physical quantity that has both magnitude and
direction

Question 2

Define a scalar quantity and give examples

Answer 2

a physical quantity that has magnitude only

Question 3

Define resultant vector

Answer 3

the single vector which has the same effect as the original vectors acting together

Question 4

What is position relative to a reference point?

Answer 4

Position describes the location of an object in relation to a chosen reference point.

Question 5

How is position represented as a vector quantity?

Answer 5

Position is a vector quantity that points from the reference point (origin) to the object’s location.

Question 6

Define distance and specify its nature.

Answer 6

Distance is the length of the path traveled, and it is a scalar quantity.

Question 7

What is displacement?

Answer 7

Displacement is the change in position of an object.

Question 8

How is displacement represented as a vector quantity?

Answer 8

Displacement is a vector quantity that points from the initial position to the final position of the object.

Question 9

Define speed and indicate its nature.

Answer 9

Speed is the rate of change of distance and is a scalar quantity.

Question 10

What is velocity, and how is it different from speed?

Answer 10

Velocity is the rate of change of position or displacement. Unlike speed, it is a vector quantity that includes both magnitude and direction.

Question 11

What is the difference between average velocity and instantaneous velocity?

Answer 11

Average velocity describes the overall motion of an object over a period, while instantaneous velocity represents the object’s velocity at a specific instant in time.

Question 12

Define acceleration.

Answer 12

Acceleration is the rate of change of velocity (indicating how an object’s velocity changes with time.)

Question 13

What is the gravitational acceleration ‘g,’ and where is it applicable?

Answer 13

Gravitational acceleration ‘g’ is approximately 9.8 m·s⁻² and applies near the surface of the Earth in the absence of air resistance.

Question 14

What is the relationship between time taken to reach the greatest height and the time taken to fall back in projectile motion?

Answer 14

In projectile motion, the time taken to reach the greatest height from the point of upward launch is equal to the time it takes to fall back to the point of launch.

Question 15

What graphs can be drawn for one-dimensional motion with constant acceleration?

Answer 15

For one-dimensional motion with constant acceleration, you can draw position vs. time, velocity vs. time, and acceleration vs. time graphs.

Question 16

How do you interpret the gradient of a given graph of motion?

Answer 16

The gradient of a graph represents the rate of change of the quantity plotted on the y-axis with respect to the quantity on the x-axis.

Question 17

What does the area under a given graph of motion indicate?

Answer 17

The area under a graph of motion represents a physical quantity or value related to the variables plotted in the graph.

Question 18

How can you determine an object’s velocity from a position vs. time graph?

Answer 18

The velocity of an object can be determined by finding the gradient of a position vs. time graph.

Question 19

How can you determine an object’s acceleration from a velocity vs. time graph?

Answer 19

The acceleration of an object can be determined by finding the gradient of a velocity vs. time graph.

Question 20

How can you determine an object’s displacement from a velocity vs. time graph?

Answer 20

The displacement of an object can be determined by finding the area under a velocity vs. time graph.

Question 21

What are the different kinds of forces often encountered in physics?

Answer 21

The different kinds of forces include weight, normal force, frictional force, applied (push or pull) force, and tension (strings or cables).

Question 22

How is weight (Fg) defined, and what does it represent?

Answer 22

Weight (Fg) is defined as the gravitational force that the Earth exerts on any object on or near its surface. It represents the force of gravity acting on an object.

Question 23

How can you calculate the weight (Fg) of an object?

Answer 23

You can calculate weight using the expression Fg = mg, where ‘g’ is the acceleration due to gravity. Near the surface of the Earth, the value of ‘g’ is approximately 9.8 m·s⁻².

Question 24

What is the normal force (FN), and in what direction does it act?

Answer 24

The normal force (FN) is defined as the perpendicular force exerted by a surface on an object in contact with it. It acts perpendicular to the surface.

Question 25

Define the frictional force (Ff) and its role.

Answer 25

Frictional force (Ff) is the force that opposes the motion of an object and acts parallel to the surface with which the object is in contact.

Question 26

What does “maximum static friction” mean, and how can you calculate it?

Answer 26

Maximum static friction refers to the maximum force of static friction that can prevent an object from moving. It can be calculated using the equation max Fs = μsN, where μs is the coefficient of static friction.

Question 27

How do you solve problems involving static frictional force when it’s less than the maximum frictional force?

Answer 27

To solve such problems, you need to consider the actual applied force or force causing motion, which is less than the maximum static friction.

Question 28

What is the difference between static and kinetic friction forces?

Answer 28

Static friction force prevents initial motion, while kinetic friction force opposes the motion of an already moving object.

Question 29

How can you calculate the kinetic frictional force?

Answer 29

The kinetic frictional force (Ffk) can be calculated using the equation Ffk = μkN, where μk is the coefficient of kinetic friction.

Question 30

How do you represent forces in a free-body diagram, and what forces should be labeled?

Answer 30

In a free-body diagram, the object of interest is represented as a dot, and all the forces acting on it are drawn as arrows pointing away from the dot. The forces should be fully named, such as weight, normal force, force A on B, friction, and air resistance.

Question 31

How do you resolve forces into parallel and perpendicular components?

Answer 31

Forces can be resolved into parallel (x) and perpendicular (y) components appropriate to the set of axes used, such as resolving the weight of an object with respect to an inclined plane.

Question 32

How can you calculate the resultant or net force in the x-direction and y-direction?

Answer 32

The resultant or net force in the x-direction is calculated as a vector sum of all components in the x-direction, and the same applies to the resultant or net force in the y-direction.

Question 33

How can you calculate the overall resultant or net force using the resultant x and y components?

Answer 33

The overall resultant or net force is calculated by combining the resultant x and y components using vector addition.

Question 34

What is Newton’s First Law of motion?

Answer 34

Newton’s First Law states that an object continues in a state of rest or uniform (moving with constant) velocity unless it is acted upon by a net or resultant force.

Question 35

What is inertia, and how does it relate to Newton’s First Law?

Answer 35

Inertia is the property of an object that causes it to resist a change in its state of rest or uniform motion. It is the basis for Newton’s First Law.

Question 36

What does Newton’s Second Law of motion state?

Answer 36

Newton’s Second Law states that when a net force (Fnet) is applied to an object of mass (m), it accelerates in the direction of the net force. The acceleration (a) is directly proportional to the net force and inversely proportional to the mass.

Question 37

How can you solve problems involving Newton’s Second Law?

Answer 37

Problems involving Newton’s Second Law can be solved using the equation Fnet = ma, where Fnet is the net force, m is the mass of the object, and a is the acceleration.

Question 38

Give examples of applying Newton’s laws to equilibrium and non-equilibrium problems.

Answer 38

Examples include discussing the importance of wearing seatbelts (using Newton’s first law) and solving problems involving objects on horizontal/inclined planes, vertical motion, and two-body systems (using Newton’s second law).

Question 39

What is Newton’s Third Law of motion?

Answer 39

Newton’s Third Law states that when object A exerts a force on object B, object B simultaneously exerts an oppositely directed force of equal magnitude on object A.

Question 40

How do you identify action-reaction pairs in accordance with Newton’s Third Law?

Answer 40

Action-reaction pairs can be identified when one object exerts a force on another, and the other object exerts an equal and opposite force on the first object.

Question 41

What are the key properties of action-reaction pairs?

Answer 41

Action-reaction pairs are equal in magnitude, act in opposite directions, act on different objects, occur simultaneously, and act along the same line.

Question 42

What is linear momentum, and how is it calculated?

Answer 42

Linear momentum is the product of the mass and velocity of the object. It’s a vector quantity in the same direction as the velocity vector. Linear momentum is calculated using the formula p = mv, where p is momentum, m is mass, and v is velocity.

Question 43

How is Newton’s Second Law expressed in terms of momentum?

Answer 43

Newton’s Second Law in terms of momentum states that the net force acting on an object is equal to the rate of change of its momentum.

Question 44

What is the law of conservation of linear momentum?

Answer 44

the total linear momentum of an isolated system remains constant (is conserved) (as long as there are no net external forces acting on it.)

Question 45

Differentiate between elastic and inelastic collisions.

Answer 45

Define an elastic collision as a collision in which both momentum
and kinetic energy are conserved
Define an inelastic collision as a collision in which only momentum
is conserved

Question 46

What is impulse, and how is it defined?

Answer 46

Impulse (J) is defined as the product of the net force and the contact time. It is a vector quantity and is in the same direction as the net force vector.

Question 47

How is impulse related to change in momentum?

Answer 47

Impulse and change in momentum are equivalent; they both represent the same physical quantity. Mathematically, J = Δp, where J is impulse, and Δp is the change in momentum.

Question 48

Give an everyday example of applying the concept of impulse.

Answer 48

An example of applying the concept of impulse is using airbags in vehicles to increase the time of collision and reduce the force applied to the occupants, enhancing safety. Another example is catching a hard ball where extending the time of contact reduces the force on your hand.

Question 49

What is the definition of work in physics?

Answer 49

Work is defined as the product of the displacement and the component of a force parallel to the displacement.

Question 50

What are the units of work, and what is its nature?

Answer 50

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

Question 51

When is the work done on an object considered positive, and when is it considered negative?

Answer 51

Work is considered positive when an object gains energy, and negative when an object loses energy.

Question 52

What is gravitational potential energy, and how is it calculated?

Answer 52

Gravitational potential energy is the energy an object possesses due to its position relative to a reference point. It is calculated as Ep = mgh, where Ep is the potential energy, m is the mass, g is the gravitational acceleration, and h is the height.

Question 53

Define kinetic energy and provide its calculation.

Answer 53

Kinetic energy is the energy an object has as a result of the object’s motion. It is calculated as Ek = (1/2)mv², where Ek is the kinetic energy, m is the mass, and v is the velocity.

Question 54

What is mechanical energy, and how is it defined?

Answer 54

Mechanical energy is the sum of gravitational potential energy and kinetic energy at a point.

Question 55

What is the law of conservation of energy, and what does it state?

Answer 55

The law of conservation of energy states that the total energy in a system cannot be created nor destroyed; it can only be transformed from one form to another.

Question 56

Explain the principle of conservation of mechanical energy.

Answer 56

In the absence of air resistance or any external forces, the mechanical energy of an object is constant.

Question 57

How is the principle of conservation of mechanical energy applied in physics?

Answer 57

The principle of conservation of mechanical energy is applied to solve problems and analyze the motion of objects when external forces like air resistance are negligible. It helps in understanding how mechanical energy remains constant during such motion.

Question 58

What does the Work–Energy Theorem state?

Answer 58

The Work–Energy Theorem states that the work done by a net force on an object is equal to the change in the kinetic energy of the object.

Question 59

How can the Work–Energy Theorem be applied in situations involving objects on horizontal and inclined planes or curved surfaces, considering frictionless and rough conditions?

Answer 59

The Work–Energy Theorem can be applied in such scenarios to analyze the changes in kinetic energy due to work done by forces, accounting for both frictionless and rough surfaces.

Question 60

When is the kinetic energy of a system increased?

Answer 60

The kinetic energy of a system is increased when the net force (Fnet) is in the same direction as the displacement (s).

Question 61

When is the kinetic energy of a system decreased?

Answer 61

The kinetic energy of a system is decreased when the net force (Fnet) is in the opposite direction to the displacement (s).

Question 62

How can conservation of energy problems be solved, especially when external forces and resistive forces are present?

Answer 62

Conservation of energy problems, including those with external and resistive forces, can be solved by applying the law of conservation of energy.

Question 63

What is the definition of power in physics?

Answer 63

Power is defined as the rate at which work is done or the rate at which energy is transferred.

Question 64

What is the unit of power, and how is it defined?

Answer 64

The unit of power is the watt (W), defined as the power when one joule of work is done in one second (1 W = 1 J·s⁻¹).

Question 65

How can power be calculated when work is done?

Answer 65

Power can be calculated using the formula P = W/t, where P is power, W is work, and t is time.

Question 66

How is power calculated when a force causes an object to move at a constant velocity?

Answer 66

When a force causes an object to move at a constant velocity, power can be calculated based on the formula P = Fv, where P is power, F is the force, and v is the velocity.

Question 67

What is efficiency, and how is it defined in physics?

Answer 67

Efficiency is defined as the ratio of output power to input power (representing the effectiveness of a system in converting input energy into useful output energy.)

Question 68

How can percentage efficiency be calculated?

Answer 68

Percentage efficiency can be calculated by dividing the useful output power by the input power and then multiplying by 100 to express it as a percentage.