Mechanics

Question 1

weight vector or scalar

Answer 1

vector

Question 2

sin, cos, along, into slope

Answer 2

sin - along slope
cos - into slope

Question 3

equilibruim

Answer 3

sum of forces = 0
sum of moment = 0

Question 4

moments

Answer 4

moments = force x perpendicular distance

Question 5

centre of mass

Answer 5

point where you can assume weight acts through

Question 6

describing curved part of velocity time graph

Answer 6

non uniform acceleration/deceleration

Question 7

suvat

Answer 7

v = u + at
v^2 = u^2 + 2as
s = ut + 1/2 at^2
s = vt - 1/2 at^2
s = 1/2(u+v) t

Question 8

object falling with drag

Answer 8

as object moves faster, drag increases until terminal velocity

Question 9

Newtons Laws

Answer 9

1
If there is no resultant force on object, velocity will stay the same
2
Resultant force on object is proportional to rate of change of momentum
F = ma
3
Force acting on A from B is equal to force acting on B from A

Question 10

momentum

Answer 10

momentum = mass x velocity
p = mv

momentum is conserved

Question 11

elastic vs inelastic collisions

Answer 11

Elastic collisions - Kinetic energy conserved
Inelastic collisions - Kinetic energy not conserved

momentum conserved in both

Question 12

Momentum and impulse equation

Answer 12

Momentum = Force x time (impulse (Ns))

Question 13

area under force time graph

Answer 13

change in momentum

Question 14

car crumple zone

Answer 14

Big force x small time = small force x big time

momentum constant
increase time to get smaller force

Question 15

upthrust

Answer 15

upthrust = weight of displaced fluid

Question 16

work done

Answer 16

W = d F

W = Fcosθ d
when force is at an angle

Question 17

Power, work

Answer 17

P=W/t

Question 18

Power, force, velocity

Answer 18

P = Fv

Question 19

energy equations

Answer 19

E = 1/2mv^2
W = Fd
E = mgh