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Brown's Physics AQA GCSE Additional SciencePHYSICS Revision Notes
Physics Unit P2.1 Forces and their effects
Study Notes
PHYSICS UNIT 2 Physics P2
for GCSE Additional Science or GCSE Physics
REVISION NOTES GUIDE SUMMARY: What do you need to know
for the examinations? What do you need to able to do in the exams? In AQA GCSE Science
A examinations HT means for higher tier students only.
Sorry, but I don't have much time to answer questions, but if you see any
apparent errors or wish to comment, please
email me. All my notes, learning
objectives, comments for exam revision are based on the official AQA GCSE Science A Key Stage 4
syllabus specification.
PHYSICS UNIT 2 Physics P2
for GCSE Additional Science or GCSE Physics
AQA GCSE Science PHYSICS 2 Unit
P2.1 Forces and their effects

Appreciate that forces can cause changes to the
shape or motion of an object.

Not only can objects can move in a straight
line at a constant speed but they can also change their
speed and/ or direction (accelerate or decelerate).

Be able to use/produce graphs can help us to describe
the movement of an object.

These may be distancetime graphs or
velocitytime graphs.

You should be able to use their skills, knowledge and
understanding to:

interpret data from tables and graphs relating to speed,
velocity and acceleration

evaluate the effects of alcohol and drugs on
stopping distances

evaluate how the shape and power of a vehicle can be
altered to increase the vehicle’s top speed

draw and interpret
velocitytime graphs for objects that reach terminal velocity, including a
consideration of the forces acting on the object.
AQA GCSE Science PHYSICS
Unit
P2.1.1 Resultant forces

a) Know and understand that whenever two objects
interact, the forces they exert on each other are equal and opposite.

b) Know and understand that a number of forces acting at
a point may be replaced by a single force that has the same effect on the
motion as the original forces all acting together.

c) Know and understand that a resultant force acting on
an object may cause a change in its state of rest or motion.

d) Know and understand that if the resultant force acting
on a stationary object is:

zero, the object will remain stationary

not
zero, the object will accelerate in the direction of the resultant force.

e) Know and understand that if the resultant force acting
on a moving object is:

zero, the object will continue to move at the same
speed and in the same direction

not zero, the object will accelerate in
the direction of the resultant force.
AQA GCSE Science PHYSICS
Unit
P2.1.2 Forces and motion

a) Know that the acceleration of an object
is determined by the resultant force acting on the object and the mass of
the object.

Be able to use the equation:

a = F / M or
F = m x a (F = ma)

a = acceleration in
metres per second squared, m/s^{2}

F = the resultant force
in newtons, N

m = mass in kilograms,
kg

b) Know and understand that the gradient of a
distance–time graph represents speed.

c) HT only: You should be
able to calculate the speed of
an object from the gradient of a distance–time graph.

d) Know that the velocity of an object is
its speed in a given direction.

e) Know and understand that the acceleration of an object
is given by the equation:

Be able to use the equation:

a = (v – u) / t

a is the acceleration in
metres per second squared, m/s^{2}

v is the final velocity
in metres per second, m/s

u is the initial velocity
in metres per second, m/s

t is the time taken in
seconds, s

f) Know and understand that the gradient of a
velocity–time graph represents acceleration.

g) HT only: Be able
to calculate the
acceleration of an object from the gradient of a velocity–time graph.

h) HT only: Be able to calculate the distance
travelled by an object from a velocity–time graph.
AQA GCSE Science PHYSICS
Unit
P2.1.3 Forces and braking

a) Know and understand that when a vehicle travels at a steady speed the resistive forces balance the driving force.

b) Know and understand that the greater the speed of a vehicle the greater the braking force needed to stop it in a certain distance.

c) Know and understand that the stopping distance of a vehicle is the sum of the distance the vehicle travels during the driver’s reaction time (thinking distance) and the distance it travels under the braking force (braking distance).

d) Know and understand that the
a driver’s reaction time can be affected by tiredness, drugs and alcohol.

e) Know and understand that when the brakes of a vehicle are applied, work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increase.

f) Know and understand that the
a vehicle’s braking distance can be affected by adverse road and weather conditions and poor condition of the vehicle.
AQA GCSE Science PHYSICS
Unit
P2.1.4 Forces and terminal velocity

a) Know and understand that the faster an object moves
through a fluid the greater the frictional force that acts on it.

b) Know and understand that an object falling through a
fluid will initially accelerate due to the force of gravity.

You should understand that eventually the
resultant force will be zero and the object will move at its terminal
velocity (steady speed).

You should understand why the
use of a parachute reduces the parachutist’s terminal velocity.

c) Be able to draw and interpret
velocitytime graphs for objects that reach terminal velocity, including a
consideration of the forces acting on the object.

d) Be able to calculate the weight of an
object using the force exerted on it by a gravitational force:

Be able to use the equation:

W = m x g
(W = mg)

W = the weight of the
object in newtons, N

m is the mass in
kilograms of the object, kg

g is the gravitational
field strength in newtons per kilogram, N/kg
AQA GCSE Science PHYSICS
Unit
P2.1.5 Forces and elasticity

a) Know and understand that a force acting on an object
may cause a change in shape of the object.

b) Know and understand that a force applied to an
elastic object such as a spring will result in the object stretching and
storing elastic potential energy.

c) Know and understand that for an object that is able
to recover its original shape, elastic potential energy is stored in the
object when work is done on the object to change its shape.

d) Know and understand that the extension of an
elastic object is directly proportional to the force applied, provided that
the limit of proportionality is not exceeded:

Be able to use the equation:

F = k x e (F = ke)

F is the force in
newtons, N

k is the spring constant
in newtons per metre, N/m

e is the extension in
metres, m


AQA GCSE Additional Science
PHYSICS

When revising, these pages
provide you with a summary of what you need to know and be able to do.

BUT remember, your primary
source of revision are your class notes, investigations and AQA GCSE
science textbooks.

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