Unit 1: Application of Forces and Transfer of Energy

A complete set of conceptual review flashcards covering natural forces, contact/non-contact forces, friction, elastic forces, gravitational field strength, mass vs. weight calculations, and magnetic forces.

How do warm oceans lead to the formation and consequences of tropical cyclones?

Warm oceans provide energy for long and powerful storms that bring heavy rains and strong winds. The heavy rains cause flooding and loosen soil leading to landslides, while strong winds exert great forces that destroy objects and cause environmental damage.

How do tectonic plates cause earthquakes and what are their impacts?

When constantly slow-moving tectonic plates slide over or against each other, the forces exerted between them lead to the release of massive amounts of energy, triggering earthquakes or tremors. The resulting intense ground shaking can cause widespread damage to buildings, infrastructure, and roadways.

What causes a volcanic eruption and in what forms is energy released?

A volcanic eruption occurs when magma, formed by the melting of rocks, is forcefully pushed out towards the Earth's surface. It releases massive energy stored within the Earth in the form of kinetic energy of the magma, heat, and light.

How are tsunamis generated and why do their waves cause extensive damage?

Earthquakes and volcanic eruptions beneath the ocean displace ocean water, resulting in tsunamis. The huge waves possess high potential energy that converts into greater kinetic energy as they travel at high speeds towards the shore, striking coastal objects with great force.

What is a landform, and how were The Twelve Apostles in Australia formed?

A landform is a natural feature or shape found on the Earth's surface created by forces in nature. The Twelve Apostles were created over time as ocean waves and strong winds gradually wore away limestone cliffs, forming arches that collapsed into towering limestone pillars.

What is the scientific definition of a force and what condition is required for a force to exist?

A force is a push or pull acting on an object. It requires interactions between at least two objects.

What is the key difference between contact forces and non-contact forces, and what are examples of each?

A contact force acts between two objects that are in physical contact with each other (e.g., friction, elastic force). A non-contact force acts between two objects that are not touching each other (e.g., magnetic force, gravitational force).

What is the SI unit of force, and what instruments are used to measure force?

The SI unit of force is the newton ($N$). Force is measured using a spring balance or a dynamometer.

What is friction, and how does surface texture affect the force of friction?

Friction is a contact force that opposes the motion between two surfaces in contact. Friction is greater when an object moves on a rough surface than on a smooth surface.

What are seven advantages of friction in everyday applications?

Friction improves grip (e.g., chalk powder absorbing moisture), prevents slipping or sliding (shoe soles on roads), enables writing (pencils/erasers), holds objects together (iron nails), slows or stops vehicles (brakes), prevents doors from closing (door stoppers), and allows vehicles to move across muddy surfaces.

What are two main disadvantages of friction?

1. Wear and tear: It causes shoes, tyres, and moving machine parts to wear out. 2. Energy wastage: It produces heat (wasting energy) and requires extra energy to move objects against the opposing force.

What are three common methods used to overcome or reduce friction?

1. Using lubricating oil or grease to make surfaces smoother. 2. Using ball bearings, rollers, or wheels to allow parts or heavy objects to move easily. 3. Using a cushion of air to reduce direct surface contact (as in hovercrafts or Maglev trains).

What is elastic force, and why is it referred to as a restoring force?

Elastic force is a contact force exerted when an object is stretched or compressed from its original shape. It is called a restoring force because it acts in the direction opposite to the applied force (push or pull) to help return the object to its original shape.

How do climbing ropes utilize elastic force to protect climbers during a fall?

When a climber falls, the climbing rope undergoes stretching and exerts an increasing elastic force in the opposite direction of the fall. This slows down the fall and reduces the impact force experienced by the climber.

What is gravitational force, and when does it become significant between objects?

Gravitational force is a non-contact force of attraction between objects possessing mass. It only becomes significant when at least one of the objects has a substantial mass (e.g., between the Earth and a car).

What is gravitational field strength ($g$), and how is it expressed?

Gravitational field strength ($g$) is the amount of gravitational force exerted on every $1\,kg$ of mass. It is expressed in newtons per kilogram ($N/kg$).

What are the gravitational field strengths ($g$) near the surfaces of the Moon, Mars, Venus, Earth, and Jupiter?

The gravitational field strengths near their surfaces are: Moon = $1.6\,N/kg$, Mars = $3.7\,N/kg$, Venus = $8.9\,N/kg$, Earth = $10\,N/kg$, and Jupiter = $24.8\,N/kg$.

What formula is used to calculate the weight of an object?

The formula is $W = m \times g$, where $W$ is weight in newtons ($N$), $m$ is mass in kilograms ($kg$), and $g$ is gravitational field strength in newtons per kilogram ($N/kg$).

How do mass and weight differ across definition, SI unit, measuring instrument, and location dependence?

Mass is the amount of matter in an object (SI unit: $kg$; measured by beam or electronic balance; remains unchanged across locations). Weight is the amount of gravitational force acting on an object (SI unit: $N$; measured by spring balance or dynamometer; varies in different locations).

How does distance from the Earth's centre affect its gravitational field strength ($g$)?

As the distance from the centre of the Earth increases (moving further into space), its gravitational field strength ($g$) decreases.

What is magnetic force, and how do magnetic poles interact with each other?

Magnetic force is a non-contact force exerted between magnets or between a magnet and magnetic substances. Like poles (north-north or south-south) repel each other (force of repulsion), while unlike poles (north-south) attract each other (force of attraction).

How do Maglev trains use magnetic forces to operate efficiently?

Maglev trains use powerful magnets to create forces of repulsion against track magnets, which lifts the train above the tracks. This reduces friction and enables high-speed, smoother travel.