Further mechanics Flashcards
What is centripetal force?
A force acting on an object that is accelerating around a circle, which always acts towards the centre of a circle
What is angular speed
Angle of an object moves through per unit time
w = v/r = 2pi/T = 2pif
Formula for centripetal force
F = mv^2/r = mw^2*r
Formula for centripetal acceleration
a = v^2/r = w^2*r
When is an object experiencing simple harmonic motion?
When its acceleration is directly proportional to its displacement however in opposite directions
These conditions are shown through the equation:
a = -w^2*x (x is displacement from equilibrium position)
How will can you represent displacement, velocity and acceleration on a graph
Shown via cosine,sin wave patterns (remember where velocity = 0 and where acceleration = 0) and that these are vector diagrams so you must have a negative axis
- remember acceleration and displacement are opposite to each other in direction
When is the formula for time period on a simple pendulum blob valid?
When the bob is displaced by a small angle (less than 10 degrees)
L = length of string
g = acceleration due to gravity
During the movement, GPE is transferred to Ek and vice versa
What are the two types of mass spring systems
Vertical and horizontal mass springs
What are the differences between the two types of mass springs
The type of energy transfer during oscillation.
- for vertical Ek is transferred to elastic potential and gravitational potential energy
- Horizontal is only converted to elastic potential.
What are the 3 types of damping
light damping - amplitude gradually decreases by small amounts
Critical damping - amplitude reduces to zero in the shortest time possible
Heavy damping - amplitude reduces slower than critical damping without any oscillations
What is free vibration and how does this link to natural frequency?
Free vibration occurs when there is no external force that is continuously acting on a system so it oscillates at its natural frequency.
What are forced vibrations
When a system oscillates due to an external driving force, the frequency of the driving force is called the driving frequency.
If the driving frequency is equal to natural frequency this is where resonance occurs
What is resonance and how does this occur
Resonance is when the amplitude of the oscillation drastically increases due to natural frequency being the same as the driving frequency
Applications of resonance:
- instruments where stationary sound waves are formed
- radios - electric circuits resonates at the same frequency as the desired broadcast frequency
- swings
How can you reduce the effects of resonance
Via damping, as damping decreases the amplitude decreases and the peak of the maximum amplitude becomes wider.
