Forces, Movement, and Shape
1. Effects of Forces (KLO 1.11)
Learning Outcomes:
- 1.11 Describe the effects of forces between bodies such as changes in speed, shape or direction.
A force is a push or a pull that one object exerts on another. Forces can cause several effects:
- Change in Speed: A force can make an object speed up (accelerate) or slow down (decelerate). E.g., kicking a football.
- Change in Direction: A force can change the direction an object moves in. E.g., hitting a tennis ball with a racket.
- Change in Shape: A force can change the shape of an object, temporarily or permanently. E.g., squeezing a sponge.
⚡ Force Effects Simulation
2. Types of Forces (KLO 1.12)
Learning Outcomes:
- 1.12 Identify different types of force such as gravitational or electrostatic.
Forces are categorised as contact forces (requiring physical touch) or non-contact forces (acting at a distance).
- Gravitational Force (Weight): Non-contact. Attraction between masses.
- Electrostatic Force: Non-contact. Between charged objects. Like repels, opposite attracts.
- Magnetic Force: Non-contact. Between magnets/magnetic materials.
- Friction: Contact. Opposes motion between surfaces.
- Air Resistance (Drag): Contact. Opposes motion through air.
- Tension: Contact. Through a stretched rope/string.
- Normal Contact Force: Contact. Surface pushing perpendicular to itself.
- Upthrust: Contact. Upward force from a fluid on an immersed object.
⚡ Interactive Force Diagram
Hover over the force arrows to see details.
3. Vector and Scalar Quantities (KLO 1.13 & 1.14)
Learning Outcomes:
- 1.13 Understand how vector quantities differ from scalar quantities.
- 1.14 Understand that force is a vector quantity.
Scalar quantities have magnitude only: distance, speed, mass, time, energy, temperature.
Vector quantities have magnitude and direction: displacement, velocity, acceleration, force.
Force is a vector — you must specify both how strong it is and which direction it acts.
⚡ Interactive Vector Explorer
Drag the arrow tip to change the vector's magnitude and direction.
4. Resultant Force (KLO 1.15)
Learning Outcomes:
- 1.15 Calculate the resultant force of forces that act along a line.
The resultant force is the single force that has the same effect as all individual forces combined.
- Same direction: Add magnitudes.
- Opposite directions: Subtract the smaller from the larger.
- Balanced (resultant = 0): No acceleration.
- Unbalanced (resultant ≠ 0): Object accelerates.
⚡ Resultant Force Visualiser
Resultant Force Calculator
5. Friction (KLO 1.16)
Learning Outcomes:
- 1.16 Know that friction is a force that opposes motion.
Friction opposes the motion (or intended motion) between two surfaces. It depends on the surfaces and the normal force pressing them together.
- Useful: Tire grip, walking, brakes, holding objects.
- Problematic: Air resistance on vehicles, engine wear, heat loss.
Friction can be reduced with lubricants (oil, grease) or smoother surfaces.
⚡ Friction Explorer
6. F = ma — Newton's Second Law (KLO 1.17)
Learning Outcomes:
- 1.17 Know and use the relationship: Force = mass × acceleration (F = m × a).
Resultant Force (F) = Mass (m) × Acceleration (a)
Force in Newtons (N) · Mass in kg · Acceleration in m/s²
⚡ Newton's Second Law Lab
F = ma Calculator
7. Weight, Mass & Gravity (KLO 1.18)
Learning Outcomes:
- 1.18 Know and use: Weight = mass × gravitational field strength (W = m × g).
Mass (kg) is the amount of matter — constant everywhere. Weight (N) is the gravitational force — varies with location. On Earth, g ≈ 9.8 N/kg.
Weight (W) = Mass (m) × Gravitational Field Strength (g)
⚡ Weight Across the Solar System
💡 Notice: your mass stays the same everywhere — only your weight changes!
W = mg Calculator
8. Stopping Distance (KLO 1.19 & 1.20)
Learning Outcomes:
- 1.19 Know that stopping distance = thinking distance + braking distance.
- 1.20 Describe factors affecting stopping distance.
Stopping Distance = Thinking Distance + Braking Distance
Thinking distance depends on speed and reaction time. Braking distance depends on speed (proportional to speed²), mass, road condition, tyre/brake condition.
⚡ Stopping Distance Simulator
9. Terminal Velocity (KLO 1.21)
Learning Outcomes:
- 1.21 Describe forces on falling objects and explain why they reach terminal velocity.
A falling object has Weight (down, constant) and Air Resistance (up, increases with speed). When they balance, the resultant is zero → constant speed = terminal velocity.
⚡ Terminal Velocity Simulator
10. Practical: Force & Extension (KLO 1.22)
Learning Outcomes:
- 1.22 Practical: investigate how extension varies with applied force for helical springs, metal wires and rubber bands.
Investigation Method
Materials: Helical spring, slotted masses, clamp stand, ruler, pointer, safety goggles.
- Hang the spring from a clamp. Measure the unstretched length.
- Add masses one at a time (each ~1 N). Allow to settle.
- Measure new length. Calculate extension = new length − original.
- Repeat for 5-6 masses. Record Force (N) and Extension (cm).
- Plot Force vs Extension graph.
⚡ Virtual Spring Experiment
Current Force: 0 N Extension: 0.0 cm
| Force (N) | Extension (cm) |
|---|
Force vs Extension Graph
11. Hooke's Law & Elastic Behaviour (KLO 1.23 & 1.24)
Learning Outcomes:
- 1.23 Know that the initial linear region of a force-extension graph is associated with Hooke's law.
- 1.24 Describe elastic behaviour as the ability to recover original shape after forces are removed.
F = k × x
k = spring constant (N/m) — stiffer spring = larger k
The linear region of a force-extension graph obeys Hooke's Law. Beyond the elastic limit (E), the material no longer returns to its original shape — it is permanently deformed.
⚡ Hooke's Law Interactive Graph
12. Knowledge Check
Answer all 10 questions below, then click Check Answers to see your score.