Further Mechanics

Question 1

A periodic driving force

Answer 1

Forced vibration

Question 2

What happens if μ increases by a factor of 9 and all other conditions are kept constant

Answer 2

Initially decreases frequency by factor of 3 and therefore to make it be a constant condition frequency would have to be increased by a factor of 3, therefore increasing the number of harmonics by a factor of 3 since F of first harmonic has reduced by ⅓.

Question 3

If spring oscillator is now in oil what happens?

Answer 3

1) Amplitude decreases as loss of energy/ increase in energy transfer

2) Max amplitude occurs at a higher frequency

Question 4

A lead ball is swung around the end of a string so it moves in a circle, discuss the motion of the ball in terms of forces and N laws and why the string wouldn’t be horizontal in practice.

Answer 4

Ball doesn’t travel in a straight line therefore a force must be acting on it (N1)
Although speed is constant, velocity constantly changes therefore is accelerating (N2) as a force is applied to the ball and therefore accelerates in the same direction.
(N3) Outward force of ball experience equal and opposite force (centripetal force).
The balls weight mg is supported by the vertical component of the tension.

Question 5

When a ball hits a smooth wall at angle elastically what happens?

Answer 5

When the ball hits the wall it transfer momentum. Due to N3 the wall then exerts a force back on the wall changing it’s momentum. This force only acts perpendicular to the wall and therefore keeps initial vertical velocity but a horizontal component that is influenced by the force exerted by the wall

Question 6

Damping def

Answer 6

Process by which an oscillating object loses energy to its surroundings. This is due to a force opposing it’s motion and therefore reducing its amplitude.

Question 7

Resonance def

Answer 7

When the frequency of the applied force to an oscillating system (from a generator) is equal to its natural frequency, the amplitude therefore increases significantly.

Question 8

Natural frequency def

Answer 8

The frequency at which an object oscillates after an initial disturbance.

Question 9

Centripetal force def

Answer 9

The resultant force responsible for an object moving in circular motion and always acts towards the centre of the objects rotation.

Question 10

Circular motion def

Answer 10

Moving in a circle at a constant linear speed