βοΈβπ₯ β’ Lesson 3.2 : Effect of Forces (Phys) Flashcards
Letβs dig a little bit deeper into the effects of forces, friction, turning effects, the centre of gravity, and the understanding of energy, work, power and pressure.
What changes can forces produce in an object?
Forces can change an objectβs size, shape, or motion.
How do you determine the resultant force along a straight line?
Add forces acting in the same direction, subtract forces acting in opposite directions.
What is friction?
Friction is a force between two surfaces that resists motion and produces heat.
What is drag?
Drag is friction acting on an object moving through a liquid or gas.
What is air resistance?
Air resistance is the friction (drag) force acting on an object moving through air.
What happens to an object if there is no resultant force?
It stays at rest or moves in a straight line at constant speed.
What is Newtonβs Second Law?
Force equals mass times acceleration (F = ma).
The force and acceleration are in the same direction.
How do you interpret a loadβextension graph for an elastic solid?
The graph shows how an objectβs extension changes with applied force.
What is the spring constant?
The spring constant (k) is force per unit extension.
Equation: k = f/x
F = Force applied to the spring (In Newtons, N)
X = Extension of the spring (in meters, m)
What is the limit of proportionality in a loadβextension graph?
The point where extension is no longer directly proportional to force.
What is the moment of a force?
The moment of a force is its turning effect around a pivot. It is calculated as:
Moment = Force Γ Perpendicular distance from the pivot
How do you apply the principle of moments to balance a beam?
Clockwise moment = Anticlockwise moment
This means: (Force Γ Distance) on one side = (Force Γ Distance) on the other side.
What does it mean when an object is in equilibrium?
An object is in equilibrium when it has no resultant force (it stays still or moves at a constant speed), and no resultant moment (it doesnβt rotate).
What is the centre of gravity?
The centre of gravity is the point where an objectβs weight appears to act.
For regular shapes:
β’ Rectangular block β Center of the block
β’ Sphere β Center of the sphere
β’ Cylinder β Middle of its height
How do you find the centre of gravity of an irregular lamina?
- Hang the lamina from a point and let it settle.
- Draw a vertical line down from where it hangs.
- Repeat from another point.
- The intersection of the lines is the centre of gravity.
How does the centre of gravity affect stability?
A lower centre of gravity = more stable (ex. race cars).
A higher centre of gravity = less stable (ex. tall objects fall easily).
What are the different ways energy can be stored?
Kinetic (moving objects), GPE (height), chemical (batteries, food), elastic (stretched springs), nuclear (inside atoms), electrostatic (charges), thermal (heat).
How is Energy Transferred?
- By forces β Mechanical work (pushing, lifting, stretching)
- By electricity β Work done in circuits
- By heating β Conduction, convection, radiation
- By waves β Electromagnetic, sound
Kinetic Energy Formula
Ek = Β½ mvΒ²
β’ m = mass (kg)
β’ v = velocity (m/s)
Gravitational Potential Energy Formula
ΞEp = mgΞh
β’ m = mass (kg)
β’ g = 9.8 N/kg (Earth)
β’ Ξh = height change (m)
What is the principle of conservation of energy?
Energy cannot be created or destroyed, only transferred between stores.
Total energy before = Total energy after
Work Done Formula?
W = Fd = ΞE
β’ F = force (N)
β’ d = distance moved (m)
β’ Work done = energy transferred
How can you obtain energy from fossil fuels?
Name advantages and disadvantages.
Process: Combustion in power plants
Energy: Heat energy β water β steam β turbine β generator β electrical power
Advantages: Reliable, high power output
Disadvantages: Non-renewable, high environmental impact (COβ emissions)
How can you obtain energy from biofuels?
Name advantages and disadvantages.
Process: Burning of organic materials (wood, crops, waste)
Energy: Chemical energy β combustion β steam β turbine β generator β electrical power
Advantages: Renewable, reduces waste
Disadvantages: Land use, deforestation, emissions
