Newton’s laws (P2.2) | OCR GCSE Combined Science A (Gateway Science) — Physics — Higher (J250)

P2.2 Newton’s laws

Summary Newton’s laws of motion essentially define the means by which motion changes and the relationship between these changes in motion with force and mass. Underlying knowledge and understanding Learners should have an understanding of contact and non-contact forces influencing the motion of an object. They should be aware of the newton and that this is the unit of force. The three laws themselves will be new to the learners. Learners are expected to be able to use force arrows and have an understanding of balanced and unbalanced forces.

Common misconceptions Learners commonly have misconceptions about objects needing a net force for them to continue to move steadily and can struggle to understand that stationary objects also have forces acting on them. Difficulties faced by learners when trying to differentiate between scalar and vector quantities is the idea of objects with a changing direction not having a constant vector value, for example, objects moving in a circle. This issue also arises with the concept of momentum and changes in momentum of colliding objects.

Reference	Mathematical learning outcomes	Maths skills
$PM2.2i$	$force (N) = mass (kg) \times^{}$

Learning outcomes	To include	Maths	Working scientifically	Practical suggestions
$P2.2a recall examples of ways in which objects interact$	$electrostatics, gravity, magnetism and by contact (including normal contact force and friction)$
$P2.2b describe how such examples involve interactions between pairs of objects which produce a force on each object$
$P2.2c represent forces as vectors$	$drawing free body force diagrams to demonstrate understanding of forces acting as vectors$	$M5b$	$WS1.2a, WS1.2b, WS1.2c, WS1.2e, WS1.3a, WS1.3c, WS1.3e, WS1.3h, WS2a, WS2b, WS2d$	$Measurement of the velocity of ball bearings in glycerol at different temperatures or of differing sizes. (PAG P3)$
$P2.2d apply Newton’s first law to explain the motion of an object moving with uniform velocity and also an object where the speed and/or direction change$	$looking at forces on one body and resultant forces and their effects (qualitative only)$		$WS1.3e, WS2a$	$Demonstration of the behaviour of colliding gliders on a linear air track. (PAG P3) Use of balloon gliders to consider the effect of a force on a body.$
$P2.2e use vector diagrams to illustrate resolution of forces, a net force (resultant force), and equilibrium situations$	$scale drawings limited to parallel and perpendicular vectors only$	$M4a, M5a, M5b$
$P2.2f describe examples of the forces acting on an isolated solid object or system$	$examples of objects that reach terminal velocity for example skydivers and applying similar ideas to vehicles$		$WS1.2a, WS1.2b, WS1.2c, WS1.2e, WS1.3a, WS1.3c, WS1.3e, WS1.3h, WS2a, WS2b, WS2d$	$Learners to design and build a parachute for a mass, and measure its terminal velocity as it is dropped. (PAG P3)$
$P2.2g describe, using free body diagrams, examples where two or more forces lead to a resultant force on an object$
$P2.2h describe using free body force diagrams the special case of balanced forces when the resultant force is zero (qualitative only)$
$P2.2i apply Newton’s Second Law in calculations relating forces, masses and accelerations$		$M1a, M2a, M3b, M3c, M3d$	$WS1.2a, WS1.2b, WS1.2c, WS1.2e, WS1.3a, WS1.3c, WS1.3e, WS1.3h, WS2a, WS2b, WS2c, WS2d$	$Use of light gates, weights and trolleys to investigate the link between force and acceleration. (PAG P2)$
$P2.2j explain that inertia is a measure of how difficult it is to change the velocity of an object and that the inertial mass is defined as the ratio of force over acceleration$
$P2.2k define momentum and describe examples of momentum in collisions$	$an idea of the law of conservation of momentum in collisions$		$WS1.2a, WS1.2b, WS1.2c, WS1.2e, WS1.3a, WS1.3c, WS1.3e, WS1.3h, WS2a, WS2b, WS2c, WS2d$	$Use of light gates, weights and trolleys to measure momentum of colliding trollies. (PAG P3) Use of a water rocket to demonstrate that the explosion propels the water down with the same momentum as the rocket shoots up.$
$P2.2l use the relationship between work done, force, and distance moved along the line of action of the force and describe the energy transfer involved$		$M1a, M2a, M3a, M3b, M3c, M3d$	$WS1.4a, WS2a, WS2b$	$Measurement of work done by learners lifting weights or walking up stairs. (PAG P5)$
$P2.2m calculate relevant values of stored energy and energy transfers; convert between newton-metres and joules$		$M1c, M3c$	$WS1.4e, WS1.4f$
$P2.2n explain, with reference to examples, the definition of power as the rate at which energy is transferred$
$P2.2o recall and apply Newton’s Third Law$	$situations of equilibrium and non-equilibrium$
$P2.2p explain why an object moving in a circle with a constant speed has a changing velocity (qualitative only)$			$WS1.3e$	$Demonstration of spinning a rubber bung on a string$

Learning outcomes

To include

Maths

Working scientifically

Practical suggestions

P2.2a recall examples of ways in which objects interact

electrostatics, gravity, magnetism and by contact (including normal contact force and friction)

P2.2b describe how such examples involve interactions between pairs of objects which produce a force on each object

P2.2c represent forces as vectors

drawing free body force diagrams to demonstrate understanding of forces acting as vectors

M5b

WS1.2a, WS1.2b, WS1.2c, WS1.2e, WS1.3a, WS1.3c, WS1.3e, WS1.3h, WS2a, WS2b, WS2d

Measurement of the velocity of ball bearings in glycerol at different temperatures or of differing sizes. (PAG P3)

P2.2d apply Newton’s first law to explain the motion of an object moving with uniform velocity and also an object where the speed and/or direction change

looking at forces on one body and resultant forces and their effects (qualitative only)

WS1.3e, WS2a

Demonstration of the behaviour of colliding gliders on a linear air track. (PAG P3) Use of balloon gliders to consider the effect of a force on a body.

P2.2e use vector diagrams to illustrate resolution of forces, a net force (resultant force), and equilibrium situations

scale drawings limited to parallel and perpendicular vectors only

M4a, M5a, M5b

P2.2f describe examples of the forces acting on an isolated solid object or system

examples of objects that reach terminal velocity for example skydivers and applying similar ideas to vehicles

WS1.2a, WS1.2b, WS1.2c, WS1.2e, WS1.3a, WS1.3c, WS1.3e, WS1.3h, WS2a, WS2b, WS2d

Learners to design and build a parachute for a mass, and measure its terminal velocity as it is dropped. (PAG P3)

P2.2g describe, using free body diagrams, examples where two or more forces lead to a resultant force on an object

P2.2h describe using free body force diagrams the special case of balanced forces when the resultant force is zero (qualitative only)

P2.2i apply Newton’s Second Law in calculations relating forces, masses and accelerations

M1a, M2a, M3b, M3c, M3d

WS1.2a, WS1.2b, WS1.2c, WS1.2e, WS1.3a, WS1.3c, WS1.3e, WS1.3h, WS2a, WS2b, WS2c, WS2d

Use of light gates, weights and trolleys to investigate the link between force and acceleration. (PAG P2)

P2.2j explain that inertia is a measure of how difficult it is to change the velocity of an object and that the inertial mass is defined as the ratio of force over acceleration

P2.2k define momentum and describe examples of momentum in collisions

an idea of the law of conservation of momentum in collisions

WS1.2a, WS1.2b, WS1.2c, WS1.2e, WS1.3a, WS1.3c, WS1.3e, WS1.3h, WS2a, WS2b, WS2c, WS2d

Use of light gates, weights and trolleys to measure momentum of colliding trollies. (PAG P3) Use of a water rocket to demonstrate that the explosion propels the water down with the same momentum as the rocket shoots up.

P2.2l use the relationship between work done, force, and distance moved along the line of action of the force and describe the energy transfer involved

M1a, M2a, M3a, M3b, M3c, M3d

WS1.4a, WS2a, WS2b

Measurement of work done by learners lifting weights or walking up stairs. (PAG P5)

P2.2m calculate relevant values of stored energy and energy transfers; convert between newton-metres and joules

M1c, M3c

WS1.4e, WS1.4f

P2.2n explain, with reference to examples, the definition of power as the rate at which energy is transferred

P2.2o recall and apply Newton’s Third Law

situations of equilibrium and non-equilibrium

P2.2p explain why an object moving in a circle with a constant speed has a changing velocity (qualitative only)

WS1.3e

Demonstration of spinning a rubber bung on a string

Newton’s laws

Next Steps

Learning Objectives