6 forces

Question 2

What do scalar quantities have ?

Answer 2

magnitude only
( size)

Question 3

what do vector quantities have

Answer 3

magnitude and associated direction

Question 6

state newtons three laws of motion

Answer 6

FIRST LAW1.if an object remains stationary or moves at constant velocity (same speed + direction) if the resultant force is 0
object either
• remains stationary
• remains moving at constant velocity
(same speed+ direction)
Newton’s second law
F=ma
acceleration is proportional to resultant force
acceleration is inversely proportional to mass
Newtons third law
when 2 objects interact, the F they exert are equal and opposite

Question 7

describe the forces action on a skydiver before and after opening their parachute

Answer 7

initially only weight or gravity acts downwards
as velocity increases air resistance does too
terminal velocity: weight= air resistance-> no acceleration
parachute opens: air res suddenly
decelerate+ new lower terminal velocity

Question 8

what factors affect braking distance

Answer 8

speed(higher) longer stopping distance
mass (heavier=longer)
wet/icy roads
worn down breaks

Question 9

how do seat belts crumple zones reduce injury

Answer 9

seatbelts increase stopping time
crumple zones absorb E which spreads impact
airbags spread F over larger SA