Page 323 - (DK) The Ultimate Visual Dictionary 2nd Ed.

FORCE AND MOTION
NEWTON’S THREE LAWS OF MOTION

NEWTON’S FIRST LAW
When no force acts on a body, it will Constant
continue in a state of rest or uniform motion. speed
Newton meter
Newton meter shows
no applied force shows no
Mass of 1 kg Mass of 1 kg applied force

Mass of trolley Trolley is not in motion, and will Trolley is in motion, and will continue at a
is negligible remain at rest until a force acts constant speed in a straight line until a force acts
NO FORCE, NO ACCELERATION: STATE OF REST NO FORCE, NO ACCELERATION: UNIFORM MOTION

NEWTON’S SECOND LAW
When a force acts on a body, the motion of the body will change. The size of the change
will depend upon the mass of the object and the magnitude of the applied force.
Trolley and mass (2 kg)
Acceleration Trolley and mass (1 kg) gain Acceleration is gain 1 meter per second of
is 2 ms -2 2 meters per second of speed 1 ms -2 speed each second (1 ms -2 )
each second (2 ms -2 )
Newton meter registers Newton meter
Mass of 1 kg force of 2 N Mass of 2 kg registers force of 2 N

With the same applied force, an object with 2 kg mass
accelerates at half the rate of object with 1 kg mass
FORCE AND ACCELERATION: SMALL MASS, LARGE ACCELERATION FORCE AND ACCELERATION: LARGE MASS, SMALL ACCELERATION

NEWTON’S THIRD LAW
If one object exerts a force on another, an equal and opposite force, Newton meters pull on each other with
called the reaction force, is applied by the second object on the first. equal and opposite forces
Acceleration: the trolley and Newton meter registers Newton meter registers
mass accelerate at 2 ms -2 force of 2 N to the left force of 2 N to the right
Mass of 1 kg

Person experiences
a reaction force
ACTION AND REACTION

THREE CLASSES OF LEVER
Fulcrum,
between effort Load is applied
and load Fulcrum at open end
Effort forces
tongs together
Effort Load, Load is smaller
between effort than effort, but
Load is and fulcrum
greater than moves through
effort, but moves Effort is smaller than load, but greater distance Effort, between
through smaller moves through greater distance fulcrum and load Fulcrum
distance
CLASS 1 LEVER CLASS 2 LEVER CLASS 3 LEVER
Pliers consist of two class 1 levers. Nutcrackers consist of two class 2 levers. Tongs consist of two class 3 levers.
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