relative velocity and stuff

newton’s first law

an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force

inertia

the resistance an object has to change in its state of motion. the more mass an object has the bigger its inertia.

calculating speed formula

v = x/t

unit for distance

metres, kilometres

unit for time

seconds, hours

unit for speed

m/s, km/h

acceleration

m/s^2

unit for force

N

unit for mass

g, kg

difference between speed and velocity

velocity: signifies both the magnitude (numerical value) of how fast an object is moving and the direction in which it is moving (vector)

speed: only magnitude (scalar)

effects of forces

1. acceleration
2. deceleration
3. changing direction
4. changing form

formula for calculating weight

F=m\*g

weight vs mass

weight: the force you have on the ground → dependant on place

mass: what you actually are → independent on place

how to measure force

has to measure its effect → measure the change in direction, the change in speed (dynamic measuring) or the deformation. dynamic measuring is not easy, as the force is moving. the effect of a force is easier to measure with a spring.

formula of hooke’s law

k = F/delta x

uniformly accelerated motion

UAM is the motion of an object where the acceleration is constant.

formulas of UAM

a = delta v/ time ; x = average speed \* t

uniform motion

if a body travels equal distance in equal intervals of time in the same direction

x and y components of a velocity vector

vx = v \* cos (alpha)

vy = v \* sin (alpha)

what is force

a vector quantity

hooke’s law statement

the force required to stretch an elastic object is proportional to the extension of the spring