Mechanics

Question 1

Scalar Quantity

Answer 1

Quantity with magnitude only, no directional component.
eg: time.

Question 2

Vector Quantity

Answer 2

Quantity with both magnitude and direction.
eg: velocity.

Question 3

Momentum

Answer 3

(p), is the product of mass and velocity.

Question 4

Principle of Conservation of Momentum

Answer 4

The total momentum before an interaction is equal to the total momentum after, provided no resultant force acts on the system.

Question 5

Force

Answer 5

(F), is that what causes acceleration.

Question 6

Newton’s First Law of Motion

Answer 6

A body will remain at rest or continue moving at a constant velocity unless acted upon by an unbalancing external force.

Question 7

Newton’s Second Law of Motion

Answer 7

The rate of change of momentum is proportional to the applied force and takes place in the direction of the force.

Question 8

Newton’s Third Law of Motion

Answer 8

For every action there is an equal and opposite reaction, action and reaction do not happen on the same body.

Question 9

Newton’s Law of Universal Gravitation

Answer 9

The force of attraction between two point masses is proportional to the product of their masses and inversely proportional to the square of the distance between them.

Question 10

Acceleration due to Gravity

Answer 10

The acceleration experienced by a body in free fall within the gravitational field of a massive body.

Question 11

Weight

Answer 11

The force equal to the product of mass and acceleration due to the gravity.

Question 12

Centre of Gravity

Answer 12

A point at which the whole weight of a body appears to act.

Question 13

Normal Reaction

Answer 13

A reactionary force which is perpendicular to that surface and is due to the weight of the object.

Question 14

Moment of Force

Answer 14

The force multiplied by the perpendicular distance to the fulcrum.
The fulcrum is a fixed point about which a rigid body (called a level) is free to rotate.

Question 15

Moment

Answer 15

The turning effect of a force / (N m)

Question 16

Lever

Answer 16

A rigid body that is free to rotate about a fixed axis.

Question 17

Couples

Answer 17

A pair of equal and opposite forces whose lines of action do not coincide.

Question 18

Torque

Answer 18

The torque of a couple (T) is equal to the magnitude of one of the forces multiplied by the distance between them.

(T=Fd)

Question 19

Conditions for Equilibrium

Answer 19

Law 1: The vector sum of the forces in any direction is zero.
(Forces up = Forces down, Forces left = Forces right)

Law 2: The vector sum of the moments about any point is zero.
(Σ Clockwise moments = Σ Anticlockwise moments)

Question 20

Density

Answer 20

mass per unit volume. (kg m^-3)

Question 21

Pressure

Answer 21

force per unit area. (Pa)

Question 22

Archimedes Principle

Answer 22

When a body is wholly or partially submerged in a fluid, it experiences an upthrust equal to the weight of the fluid displaced.

Question 23

Law of Flotation

Answer 23

The weight of a floating body is equal to the weight if the fluid it displaces.

Question 24

Bouyancy

Answer 24

The upward force on a body that is wholly or partially immersed in a fluid.

Question 25

Boyle’s Law

Answer 25

Pressure is inversely proportional to volume for a fixed mass of gas at constant pressure.

Question 26

Work

Answer 26

The product of force and displacement.

Question 27

Kinetic energy

Answer 27

The energy a body has due to its motion.

Question 28

Potential Energy

Answer 28

The energy a body has due to its position or condition.

Question 29

Principle of Conservation of Energy

Answer 29

Energy can niether be created or destroyed; it merely changes from one form to another.

Question 30

Power

Answer 30

(P), the rate at which work is done.

Question 31

Angular Velocity

Answer 31

(ω), the rate of change of angle

Question 32

Linear Velocity

Answer 32

(v), the speed of a particle in a direction perpendicular to the radius at that point.

Question 33

Periodic Time

Answer 33

(T), the time taken to do one complete revolution, cycle or oscillation.

Question 34

Centripital Acceleration

Answer 34

The acceleration of an object travelling in uniform circular motion; it is directed toward the centre of the circle.

Question 35

Centripital Force

Answer 35

The force required to maintain uniform circular motion; it is directed towards the centre of the circle.

Question 36

Kepler’s Third Law

Answer 36

The sqaure of the periodic time of a satellite’s orbit around a planet is proportional to the cube of the radius of the orbit (including the radius of the planet) and inversely proportional to the mass of the planet.

Question 37

Hooke’s Law

Answer 37

When an object is stretched, bent or deformed the restoring force (F) is proportional to the displacement (s) from its equilibrium position.

Question 38

Elastic Constant

Answer 38

(k), is the consant of proportionality between the applied force and the resulting displacement of a given spring.

Question 39

Elasticity

Answer 39

The ability of a body to resist a distorting influence or stress and to return to its original size and shape when the stress is removed.

Question 40

Simple Harmonic Motion

Answer 40

(SHM), is where the acceleration (a) of a body towards a particular point is proportional to its displacement (s) from that point.

Question 41

Amplitude

Answer 41

(A), the maximum distance that an object moves from its equilibrium position

Question 42

Frequency

Answer 42

(f), the number of cycles (or oscillations) the object completes per unit time.

Question 43

Period

Answer 43

(T) of a particle excecuting SHM is the time taken for one complete oscillation.