Topic 6: Further Mechanics Flashcards
What is impulse?
Impulse is the change in momentum
I = ∆p = F∆t = mv- mu
Derivative of impulse formula
F=ma
a = ∆v/∆t
F = m∆v/∆t
= ∆p/t
∆p = F∆t
How to work out ∆p involving conservation of momentum in two dimension?
- p before = p after (same direction)
- Resolve 2d motion in perpendicular axis (x/y)
- Solve momentum with same dimension as before
What is an elastic/inelastic collision?
Elastic collision - both momentum and KE is conserved
Inelastic collision - only momentum conserved, KE transferred into other energy types.
What is a non-relativistic particle & what is the formula from KE of this particle?
- A particle travelling below comparable speeds to light.
- KE = p²/2m
Derive the equation KE = p /2m
KE = 1/2 mv² p=mv
KE = 1/2 m x p²/m²
KE = p²/m
What is a radian?
A radian is a measure of angle. 1 rad is angle in sector where arc length = radius
How to convert from degrees to radians and vice-versa?
Degree — x π/180 — radians
Radians — ÷ π/180 — radians
What is angular velocity & formula?
- Angular velocity is the angle an object moves per unit time.
- ω = v/r
- Divide angle in circle (2π) by time taken for one full circle (T - Time period)
What is centripetal acceleration?
Centripetal acceleration acts as an object moving in a uniform circular motion. The force is directed towards the centre so acceleration is directed towards centre. Perpendicular to velocity.
How can you have centripetal acceleration at constant speed?
Velocity magnitude is the same, however direction changes. The centripetal acceleration changes direction.
Why does the speed of an object in circular motion not change?
The net/centripetal force is perpendicular to the direction of motion (velocity).
W= fdcosθ; when perpen, cos90=0; W=0
No work done by this force; no change in speed
