Further Mechanics

Question 1

What is the equation for impulse?

Answer 1

• ΔP = FΔt
• F = ma
• F = m (v-u) / t
• F = ΔP / t
• This is Newtons Second Law of motion

Question 2

How do you calculate Momentum in 2D?

Answer 2

• Break it down into the horizontal and vertical components
• Remember your components of forces rules
• Tanx = Sinx / Cosx
• If you are not given a value for mass the likelyhood is it will cancel

Question 3

How do you know if a collision is elastic or inelastic?

Answer 3

• If elastic then Total KE before = Total KE after
• If inelastic then Total KE before ≠ Total KE after

Question 4

What is the equation for KE of a non relativistic particle?

Answer 4

• E_k = p² / 2m

Question 5

How do you derive E_k = p² / 2m?

Answer 5

1. p = mv
2. p² = m²v²
3. So p²/2m = m²v² / 2m
4. = 1/2 mv²
5. Hence E_k = p² / 2m

Question 6

How do you convert degrees to radians?

Answer 6

• θ * π / 180

Question 7

How do you convert radians to degrees?

Answer 7

• θ * 180 / π

Question 8

What is angular velocity?

Answer 8

• ω = θ / t
• Angular velocity is the rate of change of angle measured in rad s^-1

Question 9

What are the equations for angular velocity?

Answer 9

• v = ωr
• T = 2π / ω

Question 10

How do you derive a = v² / r

Answer 10

Question 11

What is angular displacement?

Answer 11

• θ = s / r
• Angular displacement = Displacement / Radius

Question 12

What is required to maintain circular motion?

Answer 12

• A centripetal force provided by the resultant force acting on an object towards the centre of the circle
• Without this the object will continue on a path at a tangent to the circle

Question 13

What are the equations for centripetal force?

Answer 13

• F = ma
• F = mv² / r
• F = mrω²