mechanics

Question 1

equation for [linear] acceleration (a)? (v, t)

Answer 1

a = Δv/Δt

Question 2

equation for [linear] velocity (v)?

Answer 2

v = Δs/Δt

Question 3

suvat equations? (for linear motion)

Answer 3

v = u + at

s = 0.5(v + u)t

s = ut + 0.5a(t^2)

(v^2) = (u^2) + 2as

[there’s also s = vt - 0.5a(t^2) but that’s used less]

Question 4

equation for newton’s 2nd law of motion?

Answer 4

F = ma

Question 5

equation for momentum (p)? (m, v)

Answer 5

p = mv

where m = mass and v = velocity

Question 6

equation for force (F)? (Δp, t)

Answer 6

F = Δp/t

Question 7

equation for impulse (Δp)? (F, t)

Answer 7

Δp = Ft

(area under force-time graph)

Question 8

equation for kinetic energy (KE)? (m, v)

Answer 8

KE = 0.5m(v^2)

Question 9

equation for kinetic energy (KE)? (p, m)

Answer 9

KE = (p^2)/2m

Question 10

‘equation’ for conservation of momentum?

Answer 10

m1v1 = m2v2

Question 11

equation for work done/energy transferred (W or ΔE)? (F, s)

Answer 11

W = FΔs
or
ΔE = FΔs

where s = displacement

(work done is a SCALAR quantity even though its made up of 2 vectors bc it’s just a measure of ENERGY, which is a scalar quantity)

Question 12

equation for gravitational potential energy (GPE)? (m, h)

Answer 12

ΔGPE = mgΔh

Question 13

equation for power (P)? (E, t)

Answer 13

P = ΔE/Δt

Question 14

equation for efficiency?

Answer 14

efficiency = useful energy transferred/total energy transferred
OR
efficiency = useful power output/total power input

Question 15

equation for speed in horizontal component?

Answer 15

speed = distance / time
v = s/t

(bc g doesn’t affect horizontal so speed is constant so v = u)

Question 16

equations for speed in vertical component?

Answer 16

use suvat (bc g DOES affect vertical)

Question 17

equation for drag force (F d)? (ρ, v, C d, A)

Answer 17

F d = 0.5ρ(v^2)(C d)A

where ρ = density of fluid, v = velocity, C d = drag coefficient and A = cross-sectional area of the object

Question 18

what’s another equation for an object’s acceleration when falling?

Answer 18

a = g - K(v^2)

where g = gravitational field strength, K = k/m (K accounts for objects shape, surface texture, cross-sectional area, mass, etc) and v = velocity