Further Mechanics

Question 1

Newton’s 1st Law

Answer 1

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

Question 2

Newton’s 2nd Law

Answer 2

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

Question 3

Newton’s 3rd Law

Answer 3

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

Question 4

Force (in terms of momentum change)

Answer 4

Force = rate of change of momentum. VECTOR

Question 5

Units of momentum

Answer 5

kgms-1

Question 6

Units of rate of change of momentum

Answer 6

kgms-2

Question 7

Impulse, I

Answer 7

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

Hence Impulse = change of momentum. VECTOR

Question 8

Units of Impulse, I

Answer 8

Ns or kgms-1

Question 9

Area under a graph of force against time

Answer 9

change in momentum (p) or Impulse I

Question 10

Principle of conservation of linear momentum definition

Answer 10

In a collision (or explosion) the total momentum before equals the total momentum after, providing NO EXTERNAL forces are acting.

Question 11

Elastic collision definition

Answer 11

A collision where kinetic energy is conserved

Question 12

Inelastic collision definition

Answer 12

A collision where kinetic energy is NOT conserved.

Note: TOTAL Energy is still conserved.

Question 13

Angular speed, W

Answer 13

angle turned through per second. SCALAR

Question 14

Units of angular speed, W

Answer 14

rad s-1

Question 15

Angular speed of Earth

Answer 15

7.27x10-5 rad s-1 (2Pie over 1 day in seconds)

Question 16

Centripetal force

Answer 16

Resultant force acting towards the centre of the circular path

Question 17

Conditions for shm (simple harmonic motion)

Answer 17

1. acceleration is proportional to displacement

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

Question 18

Graph of acceleration against displacement.

Answer 18

Gradient = -(2Pie x f)^2

Question 19

Gradient of displacement against

Answer 19

Gradient of a displacement against time graph is VELOCITY

Question 20

Conditions for the time period equation of a pendulum

Answer 20

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

Question 21

Dependence of time period on amplitude of an oscillation

Answer 21

Time period of oscillation in SHM is INDEPENDENT of amplitude.

Question 22

Resonance definition

Answer 22

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

Question 23

Free oscillation definition

Answer 23

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

Question 24

Forced oscillation definition

Answer 24

oscillation due to external PERIODIC driving force

Question 25

Time Period

Answer 25

time taken for one complete oscillation

Question 26

Frequency

Answer 26

number of oscillations per second

Question 27

Amplitude

Answer 27

maximum displacement of a particle from its rest position

Question 28

Damping definition

Answer 28

Damping is when frictional forces oppose motion, dissipating energy
(Total energy of oscillating system decreases)

Question 29

Damping descriptions

Answer 29

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