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Force, Meaning (SPM Physics)

A push or pull acting on an object that can change its shape, or its state of rest or motion; a vector quantity measured in newtons (N).

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Definition

A push or pull acting on an object that can change its shape, or its state of rest or motion; a vector quantity measured in newtons (N).

Force and Motion I

In exam terms

A force is a push or a pull that can change the shape of an object or its state of rest or motion. It is a vector, so it has both size and direction, and its SI unit is the newton (N), where 1 N is the force that gives a 1 kg mass an acceleration of 1 m s⁻².

The link between force and motion is Newton's second law, F = ma, where F is the resultant force in newtons (N), m is the mass in kilograms (kg) and a is the acceleration in metres per second squared (m s⁻²). For example, a resultant force on a 3 kg trolley producing 2 m s⁻² is F = ma = 3 kg × 2 m s⁻² = 6 N.

Do not confuse it with…

Do not confuse force with pressure. Force is the total push or pull in newtons, while pressure is that force spread over unit area (pressure = force ÷ area) and is measured in pascals (Pa).

The same force gives a larger pressure when it acts on a smaller area.

Also distinguish a single force from the resultant force, which is the combined effect of several forces. In Paper 2 you may be asked to define force, or to state and use Newton's second law in a calculation; remember it is the resultant force, not one individual force, that determines the acceleration.

Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)

Frequently asked questions

Is force a scalar or a vector?
Force is a vector because it has both magnitude and direction. Two forces of the same size acting in opposite directions can cancel to give zero resultant force.
What is 1 newton in base units?
One newton is the resultant force that gives a mass of 1 kg an acceleration of 1 m s⁻², so 1 N = 1 kg m s⁻² in SI base units.
Does a force always cause motion?
No. A force can also change an object's shape, or be balanced by other forces so the resultant is zero. Only a non-zero resultant force produces acceleration.

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