Forces Basics
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Transcript of Forces Basics
ForcesYear 11 Physics
Learning Intentions• To identify the effect of forces acting
on an object
• To recall some common examples of forces
Book Reference• Page 33 Physics for CCEA
A force is a push, pull or twist.
What you should already know…
Say if the following are pushes, pulls or twists:
Writing on paper
Typing on a keyboard
Tug-of-war
Unscrewing the top off a bottle
Posting a letter through a door
Putting on a pair of socks
Turning a door handle
Pull
Pull
Push
Push
Push
Twist Twist
Twist Twist
Demos• What is the effect of the force on the
object?
• Can you name the force causing the effect?
Rocket Launcher• Start object moving
• Thrust
The Parachute Opening• Decreasing in Speed
• Air Resistance
Airplane Take-off• Changing Direction
• Lift
F1 Car• Change Shape
• Reaction Force
The effects of a forceA force can cause an object to…
• Increase/decrease in speed
• Change direction
• Change shape
• Start moving or stop moving
Learning Intentions- Identify and label forces acting on an
object
- Recall some common examples of forces
- Use a Newton balance to measure forces
Name a force
Describing the forces
1. Magnetism
2. Friction
3. Compression
4. Tension
a. When 2 material rub together
b. When a material is being stretched
c. When a material is being squashed
d. Enables compasses to work
5. Gravity
6. Nuclear
7. Air resistance
8. Electrostatic
e. Holds the particles in a nucleus together
f. When an object moves through air
g. The force that exists between all objects with mass
h. The force you get between two charged objects
Some Force definitions
When an object is moving it comes in contact with small
particles in the air. The collisions cause an opposition to the
movement.
An engine or motor uses this force to cause an object to
move.
This force is experienced when an object is in water, it is
sometimes called buoyancy.
The force associated with a string or a rope
being stretched.
The Force which opposes the motion of
an object, it is also needed to give your
shoes grip on the ground
When an object’s weight is larger than this force then the object will break
through- it is a contact force and acts in the opposite direction to
weight.
FRICTIONTENSIONUPTHRUST
THRUSTAIR RESISTANCEREACTION FORCE
Learning Intentions- Identify and label forces acting on an
object
- Recall some common examples of forces
- Use a Newton balance to measure forces
Force diagramsForce diagrams help us understand forces.
The force is represented by an arrow.
The direction the arrow points shows the direction the force is acting.
The size of the arrow can be used to compare the size of the forces.
A force diagram for a falling object just after it starts to fall.
Air resistance
Weight
Unused homework diary on a table
What force pulls down on the book?
Gravity
The diary does not move, so there must be an equal and opposite force pushing up on the diary.
What do we call this force?
Reaction force
Gravity
Reaction force
Forces on a speeding fish
Upthrust
FrictionThrust
Weight
What is thrust?
A forward push
What is upthrust?
The upwards force on a body in a liquid or a gas
Label the forces acting on the moving ship shown:
Upthrust or buoyancy
Thrust
Air resistance
Friction
Weight
Use the Force• In each of the examples draw the object
with all the forces acting on it (name and direction)
1. A man standing on a bridge (2)
2. An aeroplane flying high in the sky (4)
3. A ball falling vertically through the air (2)
4. A fishing line (2)
Measuring Forces• A force metre (also called a Newton
balance) can be used to measure the size of a force. The standard unit used for force is the newton (N)
The force that you… Size of Force (N) Name of Force
need to double the length of a spring
apply to the ground
work against to drag your bag along the desk