1.2) Forces Flashcards
What changes can force make
1.Change speed
2.Change direction
3.Change shape
Newtons first law
Every object remains in its uniform state of motion unless an external force is applied
Newtons second law
Acceleration of an object is dependent on two things, net force acting upon object and mass of object
F=ma
Newtons third law
For every action there is an equal and opposite reaction
Gravitational force
W=mg , N
Define Weight
The force of gravity on an object
Friction force
1.Friction opposes motion
2.Friction causes loss of energy as heat energy
How to reduce friction
1.Oil and greasing gears
2.Air cushion
3.Lubrication
4.Streamlining car shapes
5.Polishing surfaces
Drag force
friction between solid and liquid or gas
-As speed increases drag force increases
Factors affecting drag forces
1.Shape of object
2.Size of object
3.speed of object
4.Density of fluid
Describe and explain the motion of the ball as it falls until it reaches terminal velocity
-Ball initially accelerates due its weight
-As speed increases air resistance increases, net force decreases, acceleration decreases
-Until weight downwards=resistance force upwards, so net force = 0 and acceleration = 0, ball falls with constant speed reaching terminal velocity
Centripetal force
Force that continuously changes the direction of the object and keeps moving in a circular path
(force is towards centre of motion)
Explain why an object that moves in a circular path, is said to be accelerating, even it is moving with constant speed.
Because it continuously changes direction
so velocity is changing even if speed is constant so its accelerating
Hooks law
The extension of a metal spring is directly proportional to the applied weight
Hooks law=
F=Kx
Spring before limit of proportionality
-Force is directly proportional to extension and obeys hooks law
-if force is removed spring will return back to its original size
The spring after limit of proportionality
-Force is not directly proportional to extension and doesnt obey hooks law
-If force is removed, spring will not be back to its original side
Connecting springs in series will
Final extension will be 2x the extension
Spring in parrallel
1/2 X of the extension
