Motion

Question 1

What are the characteristics for objects moving in a circle?

Answer 1

• resultant force + acceleration towards centre
• direction of V is perpendicular to direction of F and a
• Fc is provided by some external forces

Question 2

Force is required for an object to move in circle, use Newton’s law to explain

Answer 2

1st law: if no force applied, object will move in uniform motion, so a force is needed to turn in circles

2nd law: as velocity changes, momentum changes, rate of change in momentum is force

Question 3

why the angle is different when the object travels faster

Answer 3

• needs greater centripetal force
• provided by larger horizontal component of tension
• only achieved if larger angle

Question 4

Define radian

Answer 4

angle subtended at the centre of circle by arc length 1 radius

Question 5

Define SHM

Answer 5

the oscillation motion when the acceleration is proportional to the displacement, and in opposite direction

Question 6

When is the object in resonance?

Answer 6

• natural frequency = frequency of the driver
• max.amplitude
• absorbs greatest possible energy from the driver

Question 7

What is damping?

Answer 7

amplitude of oscillation decreases due to friction

frequency does not change as amplitude decreases

Question 8

What is critical damping?

Answer 8

min. amount of damping required to return an oscillator to its equilibrium position

Question 9

What happens if under damping or overdamping?

Answer 9

under = unwanted oscillations

over=slower return to equilibrium

Question 10

Describe the graph of KE and PE

Answer 10

at t=0, max PE, min KE