2.2.2 Mechanics- Kinetics

Question 1

What is speed?

Answer 1

Constant forward movement without acceleration (constant velocity).

Question 2

What is the equation for acceleration?

Answer 2

V²-U² divided by 2x distance

Question 3

In what situation does acceleration remain constant?

Answer 3

When caused by earths gravitational attraction.

Question 4

What is gravities standard value?

Answer 4

9.8m/s²

Question 5

What is uniform circular motion?

Answer 5

Motion of an object in a circle at a constant speed, continually changing direction.

Question 6

What is uniform circular motion also known as?

Answer 6

Centrifugal/Centripetal

Question 7

What is centripetal force?

Answer 7

The force needed to keep an object moving in a circular motion and is facing in towards the centre.

Question 8

What is the difference between centripetal and centrifugal?

Answer 8

Centripetal pulls the object in like gravity, centrifugal wants to push it away.

Question 9

What is pendular motion?

Answer 9

The movement of a pendulum when it is given a small displacement and allowed to swing under gravity.

Question 10

In pendular motion what is the angular amplitude?

Answer 10

Angular displacement from rest to maximum swing position.

Question 11

In pendular motion what is the oscillation?

Answer 11

One complete swing

Question 12

In pendular motion what is the length of the pendulum?

Answer 12

Distance from pivot to bob.

Question 13

In pendular motion what is the frequency?

Answer 13

Number of cycles completed in unit time.

Question 14

Does the mass of the bob make a difference to periodic time?

Answer 14

No

Question 15

In pendular motion what is the periodic time?

Answer 15

Time taken to complete one oscillation.

Question 16

What changes the periodic time of a pendulum?

Answer 16

The length of the pendulum.

Question 17

What is damping?

Answer 17

Decrease of oscillations as a result of removing energy through resistance to motion.

Question 18

What is free vibration?

Answer 18

When a mechanical system is set off with an initial input and then allowed to vibrate freely.

Question 19

What is forced vibration?

Answer 19

When a continuous force is applied to a mechanical system.

Question 20

What is a harmonic?

Answer 20

Periodic vibration. Sinusoidal with constant amplitude.

Question 21

What are the two waves in a harmony?

Answer 21

The harmonic and the fundamental frquency?

Question 22

What is resonance?

Answer 22

The tendency of system to oscillate at a max amplitude at a certain frequency.

Question 23

What is the equation for wavelength of a harmonic?

Answer 23

2 divided by index of harmonic x length of the body

Question 24

What is the equation for resonance frequency?

Answer 24

1 divided by 2π x square root of gravity divided by length.

Question 25

What happens if a aircraft component vibrates at its resonant frequency?

Answer 25

The oscillations will become really large and the component could be destroyed.

Question 26

What do machines do?

Answer 26

Let us do more work easily but not reduce the amount of work.

Question 27

What is the velocity ratio?

Answer 27

The ratio of the distance moved by the point of application of the effort.

Question 28

What does it mean if the velocity ratio is greater than one?

Answer 28

The distance moved by the point of effort is greater than the distance moved by the load.

Question 29

What is the equation for mechanical advantage?

Answer 29

Resistance/Effort

Question 30

What is actual mechanical advantage?

Answer 30

Tells us how much easier the work can be done.

Question 31

What is the equation for mechanical advantage?

Answer 31

Output force/ Input force

Question 32

What is ideal mechanical advantage and what is the equation?

Answer 32

Mechanical advantage if there were no resistance in the machine. Input distance/output distance

Question 33

What is a lever?

Answer 33

Rigid bar capable of turning around a fulcrum.

Question 34

What are the parts of the lever?

Answer 34

Fulcrum, force and effort.

Question 35

How do you calculate the effort required to lift a weight using a lever?

Answer 35

Work out the moments...Effort x length of arm = Resistance x length of arm

Question 36

If a question asks what is the mechanical advantage what steps must you take?

Answer 36

Rearrange the opposing moments formula to find effort: F1 = F2 x S2 divided by S1. This will give you the effort which can then be used in MA= R/E.

Question 37

What is a second class lever.

Answer 37

Fulcrum at one end rather than in the middle, i.e a wheelbarrow.

Question 38

What is an inclined plane?

Answer 38

A surface inclined to a horizontal plane at any angle but 90 degrees.

Question 39

What is a spur gear?

Answer 39

Teeth cut straight and used to connect two parallel shafts, they will turn in opposite directions.

Question 40

If you want spur gears to turn in the same direction what must one of them have?

Answer 40

Internal teeth.

Question 41

What is a bevel gear?

Answer 41

Teeth cut into a conical surface known as the pitch zone.

Question 42

Where are bevel gears used?

Answer 42

Transmit forces perpendicular to one another.

Question 43

What is worm gear?

Answer 43

Steering rack.

Question 44

When is a worm gear used?

Answer 44

When a large reduction in speed is needed and for high toque multiplication.

Question 45

What is the input gear in sun and planet gears?

Answer 45

The sun.

Question 46

How does sun and planet gears work?

Answer 46

Planet gears are held together by a cage driven around the sun gear and engage at their outer edge in a fixed ring gear which does not rotate.

Question 47

What is the output of a sun and planet gear?

Answer 47

The cage which is rotating slower than but in the same direction as the sun.

Question 48

What is an example of a sun and planet gear?

Answer 48

Propeller reduction gear.

Question 49

Where are sun and planet gears used?

Answer 49

Where space and weight is an issue but a large amount of speed reduction and torque is required.

Question 50

What is efficiency?

Answer 50

Ratio of work which is transferred to a useful form compared to the total input work.

Question 51

Why can't any machine be 100% efficent?

Answer 51

Loses like heat, friction, deflection and wear and tear.

Question 52

What is a third class lever?

Answer 52

The effort is applied at the fulcrum. i.e. landing gear.

Question 53

How do you work out the mechanical advantage of gears?

Answer 53

Driven gear teeth divided by drive gear teeth.