Flashcards in Further Mechanics (Unit 4) Deck (34):

1

## Newton’s 1st Law

### An object remains at rest or in uniform motion unless acted on by a force

2

## Newton’s 2nd Law

### The rate of change of momentum of an object is proportional to the resultant force on it

3

## Newton’s 3rd Law

### When two objects interact they exert equal and opposite forces on each other

4

## Force (in terms of momentum change)

### Force = rate of change of momentum. VECTOR

5

## Units of momentum

### kgms-1

6

## Units of rate of change of momentum

### kgms-2

7

## Impulse, I

###
Force x time for which the force acts (F(delta)t)

Hence Impulse = change of momentum. VECTOR

8

## Units of Impulse, I

### Ns or kgms-1

9

## Area under a graph of force against time

### change in momentum ((delta)p) or Impulse I

10

## Principle of conservation of linear momentum definition

### In a collision (or explosion) the total momentum before equals the total momentum after, providing no external forces are acting.

11

## Elastic collision definition

### A collision where kinetic energy is conserved

12

## Inelastic collision definition

###
A collision where kinetic energy is not conserved.

Note: Total Energy is still conserved.

13

## Angular speed, w

### angle turned through per second. SCALAR

14

## Units of angular speed, w

### rad s-1

15

## Centripetal force

### Resultant force acting towards the centre of the circular path

16

## Conditions for shm (simple harmonic motion)

###
1. acceleration is proportional to displacement

2. acceleration is in opposite direction to displacement OR acceleration always acts towards the equilibrium position.

17

## Relating a= -(2(Pi)f)2 x, to definition of shm

###
1. acceleration is proportional to displacement

a directly proportional to x and hence a = kx, where k is a constant (2(Pi)f)2.

2. acceleration is in opposite direction to displacement

minus sign indicates that acceleration, a, is in opposite direction to displacement, x.

18

## Graph of acceleration against displacement.

### Gradient = -(2(Pi)f)2

19

## Gradient of displacement against time

### Gradient of a displacement against time graph is velocity

20

## Graphical representations linking x, v, a and t

### Check Sheet

21

## Conditions for the time period equation of a pendulum

### Time Period equation for a pendulum is only true for oscillations with a small amplitude, that is, angular displacements less than 10 degrees.

22

## Dependence of time period on amplitude of an oscillation

### Time period of oscillation in SHM is independent of amplitude.

23

## Variation of Ep and Ek with displacement

### Check Sheet

24

## Variation of Ep and Ek with time

### Check Sheet

25

## Resonance definition

### When the driving frequency equals the natural frequency of an oscillating system, vibrations with large amplitude are produced

26

## Free oscillation definition

###
oscillations with a constant amplitude because there are no frictional forces and hence no energy loss.

(Total energy of oscillating system remains constant).

27

## Forced oscillation definition

### oscillation due to external periodic driving force

28

## Time Period

### time taken for one complete oscillation

29

## Frequency

### number of oscillations per second

30

## Amplitude

### maximum displacement of a particle from its rest position

31

## Damping definition

###
Damping is when frictional forces oppose motion, dissipating energy

(Total energy of oscillating system decreases)

32

## Damping descriptions

###
Light damping : takes a long time for the amplitude to decrease to zero. System oscillates at natural frequency.

Critical damping : shortest time for amplitude to decrease to zero.

Heavy damping : takes a long time for amplitude to decrease to zero. No oscillating motion occurs.

33

## Phase difference between driver and driven oscillations

### Check Sheet

34