Basic Concepts

Question 1

What are the SI units for :

a) time
b) distance
c) angle
d) temperature

Answer 1

A) second
B) Metre
C) Radian
D) Kelvin

Question 2

What is another name for the rectangular co-ordinate system?

Answer 2

Cartesian co-ordinate system

Question 3

What is the origin in the context of coordinates?

Answer 3

the point where all axes cross

Question 4

What is formed where two planes cross each other?

Answer 4

a straight line

Question 5

What is a plane?

Answer 5

a flat surface with zero thickness

Question 6

What do polar coordinates systems take into account?

Answer 6

angle and rotation

Question 7

What is displacement?

Answer 7

a vector quantity for distance where the “as the crow flies” distance is taken

Question 8

what is velocity?

Answer 8

the rate of change of displacement

Question 9

What is the equation for average velocity?

Answer 9

change in displacement/time

Question 10

What is the equation for average acceleration?

Answer 10

Change in velocity/time

Question 11

What two effects will a force have acting on an object?

Answer 11

change the position of the object

deform the shape of the object

Question 12

What is the SI unit of Force?

Answer 12

Newton

Question 13

What is the branch of physics that deals with forces and moments acting on objects at rest or moving at a constant velocity?

Answer 13

Statics

Question 14

What is the first condition of static equilibrium?

Answer 14

the sum of all external forces acting on an object is zero

Question 15

What is translational equilibrium?

Answer 15

equilibrium along straight lines

Question 16

What is Newton’s 3rd Law?

Answer 16

Every action has an equal and opposite reaction

Question 17

What is the SI unit of mass?

Answer 17

kilogram

Question 18

What is weight?

Answer 18

W=mg

Question 19

What is the equation for density?

Answer 19

p=mass/volume

Question 20

What is gravity?

Answer 20

the acceleration due to the gravitational attraction between two bodies

Question 21

What happens to gravity as mass increases?

Answer 21

Increases

Question 22

what is centre of mass?

Answer 22

the point where all the mass of the object can be assumed to act - an average of mass distribution across an object

Question 23

What is centre of gravity?

Answer 23

the point where the weight of the body can be assumed to act - a body only has a centre of gravity in a gravitational field

Question 24

Where are the centres of mass and gravity located if a body has both?

Answer 24

The same point

Question 25

What is pressure?

Answer 25

Force per unit area

Question 26

What is the equation for pressure?

Answer 26

Pressure = force/area

Question 27

What is the SI unit for pressure?

Answer 27

Pascal (Pa)

Question 28

What kind of unit is the Pascal?

Answer 28

A derived SI unit

Question 29

What happens to the pressure exerted when someone stands on one foot?

Answer 29

Pressure under the remaining foot doubles

Question 30

What is the moment of a force?

Answer 30

the tendency of a force to produce rotation about an axis

Question 31

What is another name for moment?

Answer 31

torque

Question 32

What is the SI unit for moment?

Answer 32

N m (newton metres)

Question 33

What is the equation for moment?

Answer 33

Moment = Force x Moment Arm M = F x d

Question 34

What is the second condition of static equilibrium?

Answer 34

the sum of all external moments acting on a body must be zero

Question 35

Describe a lever system

Answer 35

It consists of a rigid bar that pivots about a fulcrum (which can be likened to a pivot or hinge) and is acted on by an effort force and a resistance force. The effort force and resistance force produce moments acting about the fulcrum. The length of the line that passes through the fulcrum and is perpendicular to the effort force is called the effort arm. Similarly the length of the line that passes through the fulcrum and is perpendicular to the resistance force is called the resistance arm.

Question 36

What is a mechanical advantage?

Answer 36

When the magnitude of the effort force required to overcome a given resistance force is smaller than the magnitude of the resistance force. The effort arm is longer than the resistance arm

Question 37

What is an example of a lever with mechanical advantage?

Answer 37

a crowbar

Question 38

What is a mechanical disadvantage?

Answer 38

When the resistance arm is longer than the effort arm then the resistance may be moved through a relatively large distance.

Question 39

How can the mechanical advantage be calculated?

Answer 39

MA = effort arm/resistance arm

Question 40

How can the force exerted by muscles be calculated from MA and moments?

Answer 40

F = W x dR/dE

Question 41

What is a first class lever? give examples

Answer 41

Where the fulcrum is located between the effort and the resistance scissors see-saw crowbar

Question 42

What is a second class lever? give examples

Answer 42

resistance located between the effort and the fulcrum wheelbarrow nutcracker

Question 43

Does a second class lever work at an advantage or a disadvantage?

Answer 43

ALWAYS a mechanical advantage

Question 44

What is a third class lever? give examples

Answer 44

A third class lever has the effort located between the fulcrum and the resistance fishing rod tweezers

Question 45

Does a third class lever work at a disadvantage or an advantage?

Answer 45

ALWAYS a mechanical disadvantage