King Charles I School Knowledge Organiser
SCIENCE Introduction to Physics autumn 1
Measuring Forces
Forces can change the shape of objects and
change the way they are moving.
Forces can be a push or a pull (e.g. you pull a
chair from under a desk or you push a door
open).
Forces can be measured using a meter. The
unit of force is Newtons (N). The bigger the
force applied, the longer the spring
stretches and the bigger the reading.
Friction
including air resistance, affect motion and which may be
useful or not
 Describe factors to increase and decrease
friction (mass, surface area)
Whenever an object moves against another object, it
feels frictional forces. These forces act in the
opposite direction to the movement. Friction makes
it harder for things to move.
Useful friction – shoes and floor, brakes and wheels
Unhelpful frictional – produces heat nd noise
Reducing air resistance (drag) = streamline (e.g. modern
car shape, cycle helment),
Balanced and unbalanced forces
We can show the forces acting on an object
using a force diagram (arrows show the size and
direction of the force). Balanced forces means
the object is not moving or continues to move in
the same speed and direction. Resultant force
is the overall forces (e.g. if 50N acceleration
and 30N firction the movementWeight
forwardand
si 20N)
Gravity
Density
float or sink using ideas about relative density
to
Objects float in water when their weight is
balanced by the upthrust from the water.
The object will sink until the weight of the
water it pushes out of the way is the same
as the weight of the object.
People often confuse mass and weight. Remember that weight is a force, and is measured
in Newtons. Mass is measured in kilograms (kg). Mass is the amount of ‘stuff’ an object
contains
Gravity is the forces that attacts all obejcts to each other. Even you attract other
objects to you because of gravity, but you have too little mass for the force to be very
strong. Gravity only becomes noticeable when there is a really massive object like a moon,
planet or star. We are pulled down towards the ground because of gravity.
Weight is a force caused by gravity. The weight of an object is the gravitational force
between the object and the Earth. The more mass the object has the greater its weight
will be.
weight (N) = mass (kg) × gravitational field strength (N/kg)
Remember your mass will stay the same unless you have less atoms in the object than
before
Speed
Forces in springs
Distance = speed x time
Proportional relationship between load
and extension of a spring
King Charles I School Knowledge Organiser
SCIENCE Introduction to Physics autumn 1