Forces and motion

what is the stopping distance of a vehicle made up of?

the thinking distance + braking distance

what factors affect vehicle braking distance?

speed, mass, road condition and reaction time

what influences thinking distance?

tiredness, age, intake of alcohol/drugs, distractions

why do falling objects reach a terminal velocity?

the force of air resistance increases with speed, eventually becoming equal and opposite to the force of gravity.

what is Hooke’s Law (spring force)?

The force applied to a spring is directly proportional to the distance it is stretched.

What is the spring constant?

A measure of the spring’s stiffness- a higher value means a stiffer spring

Elastic behaviour

a material's ability to return to its original shape/ size after a deforming force is removed

elastic limit

the maximum stress a material can withstand without permanent deformation

inelastic deformation

A permanent change in shape or size that remains after the force is removed. 

how are momentum and safety features in a car related?

A vehicle with higher mass/ velocity has greater momentum, causing a larger change during a crash

Safety features like airbags/seatbelts/crumple zones increase impact time for a gradual stop.

what is the equation for force, change in momentum and time taken?

f= m(v-u)/t

what is newton’s third law?

When one object exerts a force on another object it will exert a force that is equal in magnitude and opposite in direction

what is the equation for moments?

moment = force x perpendicular distance from the pivot

what is the centre of gravity?

the point where the object's entire weight is concentrated

what is the centre of mass?

the average position of all the mass in an object

what is the principle of moments?

for an object to be in equilibrium, clockwise moments = anticlockwise moments around a pivot point

what is newton’s second law?

the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass

what is momentum recoil?

The backward movement of an object is due to the conservation of momentum when another part of the system is propelled forward

equation for recoil velocity

m₁v₁ = -m₂v₂

momentum definition

a measure of how much mass is in motion

what is the difference between vector and scalar quantities?

scalar quantity only has a magnitude

vector quantity has both magnitude and direction