Vector — has magnitude AND direction. Examples: velocity, displacement, force, acceleration, momentum.
Vectors are drawn as arrows — length represents magnitude, arrow shows direction.
Resultant force — the single force that has the same effect as all forces acting combined.
Balanced forces (resultant = 0) → object moves at constant velocity or stays still.
Unbalanced forces (resultant ≠ 0) → object accelerates in direction of resultant.
Moments and centre of mass
Moment = Force × perpendicular distance from pivot. Unit: Nm.
Clockwise moments = anticlockwise moments for a balanced object (principle of moments).
Centre of mass — the point where the weight of an object appears to act.
Suspended objects come to rest with their centre of mass directly below the pivot.
Objects topple when their centre of mass moves outside the base — wide base and low CoM = more stable.
Exam questions — 4 questions · 12 marks
⚡ Extended questions included. Show all working for calculation questions. The AI marks against the real AQA mark scheme.
1 markVector vs scalarAQA 8463 P2 style
Which pair of quantities are both vectors?
A Speed and velocity
B Force and acceleration
C Mass and weight
D Distance and displacement
3 marksResultant forceAQA 8463 P2 style
A car of mass 1200 kg has a driving force of 3000 N forwards and a friction force of 800 N backwards. Calculate (a) the resultant force and (b) the acceleration of the car. (3 marks)
Hint: (a) Subtract opposing forces. (b) Use F = ma, rearranged as a = F/m.
+30 XP
4 marksMoment calculationAQA 8463 P2 style
A 3 m uniform beam is balanced on a pivot at its centre (1.5 m from each end). A 60 N weight hangs 1.5 m to the left of the pivot. Calculate the force F that must be applied 0.5 m to the right of the pivot to balance the beam. (4 marks)
Hint: Moment = force × distance from pivot. Set clockwise = anticlockwise moments and solve for F.
+40 XP
1 markCentre of mass stabilityAQA 8463 P2 style
Why is a racing car designed with a very low centre of mass and a wide wheelbase?
A To reduce air resistance and allow higher speeds
B To make the car heavier so it has more grip
C A low centre of mass and wide base means the car can tilt further before the centre of mass moves outside the base — making it much harder to topple