IP Combined Science Notes (Lower Sec, Year 1-2): 07) Forces, Motion & Simple Machines

Study guide12 Dec 2025, 00:00 Z

Resolve forces, calculate speed and acceleration, and evaluate moments plus mechanical advantage.

Download PDF Join our Telegram study group

Q: What does IP Combined Science Notes (Lower Sec, Year 1-2): 07) Forces, Motion & Simple Machines cover?
A: Resolve forces, calculate speed and acceleration, and evaluate moments plus mechanical advantage.

Physics of everyday motion hinges on clear diagrams and consistent units. Develop habits for vector addition, graph interpretation, and machine efficiency.

These notes align with MOE's Lower Secondary Science syllabus themes commonly taught in IP Sec 1-2, and act as a bridge into upper-secondary Physics, Chemistry, and Biology.

Status: MOE Lower Secondary Science syllabus (current release) checked 2025-11-30 - scope unchanged; remains the reference for these combined science notes.

New to the Integrated Programme? Start with What is IP? | Browse all free IP notes.

The core idea is simple: Forces explain changes in motion.

Use it as a working check: Draw the forces first, find the resultant force, then decide whether the object stays still, moves at constant velocity, or accelerates.

Then go one layer deeper: Example: a velocity-time graph gives acceleration from its gradient and displacement from the area under the graph. Do not mix those two readings.

Learning targets

Differentiate scalar and vector quantities with examples.
Use $\pu{m.s-1}$ and $\pu{m.s-2}$

Reviewed by

Ezekiel Tan·Academic Advisor (Biology)

Sources

MOE - 2021 G2G3 Lower Secondary Science Syllabus (updated Apr 2024) (PDF)

Quantity	Definition	Formula
Speed (scalar)	Rate of change of distance.	$v = \frac{d}{t}$
Velocity (vector)	Rate of change of displacement.	Includes direction.
Acceleration	Rate of change of velocity.	$a = \frac{\Delta v}{\Delta t}$

Graph type	What to read	What it tells you	Trap to avoid
Distance-time graph	Gradient	Speed	Do not use area under a distance-time graph.
Velocity-time graph	Gradient	Acceleration	Check whether the line is sloping up, sloping down, or flat.
Velocity-time graph	Area between the graph and time axis	Displacement, or distance if velocity stays positive	Split the shape into triangles and rectangles before adding.

Situation	Gradient calculation	Write as acceleration	Write as deceleration
Speed increases from $\pu{0 m.s-1}$ to $\pu{12 m.s-1}$ in $\pu{6 s}$	$\dfrac{12-0}{6}$	$\pu{2.0 m.s-2}$	Not deceleration.
Speed decreases from $\pu{22 m.s-1}$ to $\pu{0 m.s-1}$ in $\pu{3.5 s}$
Speed stays constant	$\dfrac{0}{\Delta t}$	$\pu{0 m.s-2}$

Direction	Balanced pair	Result
Vertical	normal contact force = weight	no vertical acceleration
Horizontal	pull from rope = friction	no horizontal acceleration

Question clue	First setup	What to compare	Common trap
Lever or seesaw is balanced	Put clockwise moments on one side and anticlockwise moments on the other	$\text{Force} \times \text{distance}$ for each side	Adding forces directly instead of comparing moments.
Force is not acting at right angles to the lever	Use the perpendicular distance to the line of action	Moment depends on the shortest distance from pivot to force line	Using the slanted length of the lever without checking perpendicular distance.
Force acts through the pivot	Distance from pivot is zero	Moment is zero	Giving a turning effect just because the force is large.
Several forces act on the same side	Add their moments if they turn the object the same way	Total clockwise or total anticlockwise moment	Cancelling forces before checking where they act.

IP Combined Science Notes (Lower Sec, Year 1-2): 07) Forces, Motion & Simple Machines

Learning targets

Sources

1 Motion basics

Distance-time & velocity-time graphs

Motion graph checkpoint

Deceleration sign checkpoint

Worked example - Velocity-time area

2 Forces & Newton's laws

Diagram - Box pulled at constant speed

Worked example - Elevator problem

3 Moments & equilibrium

Moment setup checkpoint

Worked example - Seesaw balance

4 Simple machines

Machine ratio checkpoint

Pulley example

Try it yourself

Related Posts

Quantity	What it compares	Use it when the question asks	Common trap
Mechanical advantage	Load force divided by effort force	How much the machine multiplies force	Thinking a higher MA always means a more efficient machine.
Velocity ratio	Effort distance divided by load distance	How far the effort moves compared with the load	Using force values in the VR formula.
Efficiency	Useful output work divided by input work	How much input work becomes useful output work	Forgetting to multiply by $100\%$ .