Mechanics and waves Flashcards

1
Q

What is the centre of gravity

A

A point on the object where gravity appears to act generally in the middle but not always

2
Q

Why is a tall glass easily toppled

A

It is easily toppled when the line of action of its weight is beyond the edge of the base then the glass tips right over

3
Q

Definition of moment

A

The product of the force * the perpendicular distance from the pivot

4
Q

What is the eqaution for moments

A

Moments = FD

5
Q

What is the pivot point

A

The point of Whitchurch an object rotates about

6
Q

How do you know when an object is equilibrium

A

When the sum of clockwise moments equals the sum of anti-clockwise moments and there is no resultant force

7
Q

How would you calculate the centre of mass of a piece of card

A

Hang up the card and suspend a plumb line from the same place
Mark the position of the thread
Repeat the above steps with the card suspended from different places
Where these lines intersect is the centre of mass

8
Q

Definition of equilibrium

A

No resultant force
No resultant moment

9
Q

What is the eqaution for momentum

A

P = mass * velocity

10
Q

How do you work out velocity.

A

Total distance / total time

11
Q

How do you work out GPE

A

GPE = MGH

12
Q

How do you work out Ke

A

1/2 Mvsqaured

13
Q

What is a scalar measurement

A

An amount just with a magnitude
Energy work done
Distance around a circle

14
Q

What is vector measurement

A

An amount with a direction
Distance you are form the start of circle

15
Q

What is an example of a scalar measurement

A

Speed

16
Q

What are examples of vector measurements

A

Displacement
Force
velocity
Acceleration

17
Q

What is the change in momentum also called

A

An impulse

18
Q

How can you calculate F

A

F= impulse/time

19
Q

What is the equation for momentum

A

Mass * velocity

20
Q

What are the three conservation laws

A

Conservation of energy
Conservation of moments in equilibrium
Conservation of momentum

21
Q

What does the conservation of energy state

A

The total energy after something happens is equal to the total energy before something happens

22
Q

What does the conservation of moments in equilibrium state

A

Anti-clockwise moments are equal to clockwise moments

23
Q

What does the conservation of momentum state

A

The total momentum before something is happening is eqaul to the total momentum of something after it happens

24
Q

How do you calculate the distance from a graph

A

Area under the graph

25
Q

What is the spring extension in terms of measured length and original lengthe

A

Measured length - original length

26
Q

How do you know when an object is in equilibrium

A

If it’s centre of mass is vertically above the pivot point

27
Q

Definition of equilibrium

A

Resultant force on something is zero and the resultant, turning affect on something is zero

28
Q

What happens to the acceleration of a stone when it falls

A

Celebration stays the same never increasing or decreasing the velocity increases while gravity is 9.8

29
Q

Definition of amplitude

A

From the average position of the crest or distance, measured from average position to the trough

30
Q

Definition of wavelength

A

The distance between two corresponding points on the wave and is measured in metres

31
Q

Definition of frequency

A

This is how many waves pass by every second and is measured in hertz

32
Q

Definition of transverse waves

A

When the displacement is it, a right angle to the direction of the wave is energy travelling

33
Q

Definition of longitude waves

A

When the displacement is parallel to the direction of the wave

34
Q

How do you calculate the wave velocity?

A

Frequency * wavelength

35
Q

What are wave describes as around a fixed point?

A

Oscillation and vibration

36
Q

What are examples of oscillation and vibration Waze?

A

Ripples cause particles of water to oscillate up and down sound waves cause particles of a to vibrate back and forth

37
Q

The toy dog bobbing up and down on top of the surface of some water as waves pass it underneath, explain how the toy dog demonstrates that we do not transfer matter

A

Step one identified the wave.
The type of wave on the surface of a body of water is a transverse wave, because the duck is moving perpendicular to the direction of the wave step to describe the motion of the toy doc, the plastic duck moves up and down, but does not travel with the wave step three explain how this motion demonstrates the waves do not transfer matter both transverse and longitudinal waves transfer energy but not the particles of the medium. This means when a wave travels between two points no matter actually travels with it the points on the way you just vibrate back-and-forth about fix positions objects floating on the water that simply pop up and down when the waves pass underneath them, demonstrating that there is no movement of matter in the direction of the wave only energy.

38
Q

What is the definition of defimition

A

When the displacement is it, a right angle to the direction of the waves energy travelling

39
Q

What is three processes of waves when they interact with other objects

A

Reflection, refraction diffraction

40
Q

What is the law of reflection?

A

The angle of incidence equals the angle of reflection

41
Q

How do you find the angle of incidence?

A

Always measured from the ray to the normal

42
Q

How do you mark the normal?

A

It is always at a right angle to the boundary

43
Q

In refraction flight goes on from the normal what happens to it?

A

It’s slows down then speeds up, but doesn’t bend because doesn’t go in at an angle

44
Q

What happen when waves across a Boundry and slow down

A

Play Ben towards does a normal

45
Q

What happens to the beam after the change in angle from a refraction?

A

the frequency stays the same wavelength before is bigger than the wavelength after the velocity before is greater than the velocity after

46
Q

What is a medium?

A

Something the waves will travel through

47
Q

What is the difraction?

A

Maximum the fraction is the weather like disperses greatly after going through a gap in the wall. If the gap is small, you get maximum diffraction, but if the gap is big, you get minimum diffraction