Physics: Density, Forces, Energy, and Thermal Expansion

Comprehensive review flashcards covering density calculations, types of forces, Hooke's Law, the principle of moments, work, power, kinetic and potential energy, renewable and non-renewable energy resources, states of matter, and thermal expansion applications.

Density is defined as __________ per unit volume.

mass

The standard unit for measuring density ($\rho$) is __________.

$$\text{kg/m}^3$$

Ice floats on water because the density of ice is __________ than the density of water.

less

A stone with a mass of $12\,\text{g}$ and a density of $3\,\text{g/cm}^3$ is gently lowered into $25\,\text{cm}^3$ of water in a measuring cylinder, yielding a new reading of __________.

$$29\,\text{cm}^3$$

Force is an interaction that causes a change in an object's motion, and its SI unit is the __________.

newton ($\text{N}$)

According to Newton's second law, resultant force equals mass multiplied by __________ ($F = ma$).

acceleration

On an aeroplane, the artificial force generated by the wings is __________, while the jet engine generates thrust.

lift

Friction is the force produced when different surfaces rub against one another and always acts __________ motion.

against

The spring constant is defined as force per unit extension, represented by the formula $k =$ __________.

$$\frac{F}{x}$$

On a load-extension graph, the __________ is the point beyond which force is no longer directly proportional to extension.

limit of proportionality

A temporary change in shape that is self-reversing after removing the applied force is called __________ deformation.

elastic

The driving force used to overcome the drag and weight of an aircraft to move it through the air is called __________.

thrust

The attraction or repulsion that acts between two charged particles is known as __________ force.

electrostatic

The moment of a force is calculated as the force multiplied by the __________ distance from the pivot.

perpendicular

The Principle of Moments states that when a body is balanced, the total clockwise moments equal the total __________ moments.

anticlockwise

In the balanced see-saw shown, Person A of weight $1000\,\text{N}$ is seated $1\,\text{m}$ to the right of the pivot, so Person B of weight $500\,\text{N}$ must sit at a distance of __________ to the left.

$$2\,\text{m}$$

Work done is defined as the product of force and the distance moved in the __________ of the force.

direction

Power is defined as the rate of doing work or using up energy, and its SI unit is the __________.

watt ($\text{W}$)

The principle of conservation of energy states that energy cannot be created nor destroyed; it can only be __________ into another form.

transformed

The equation used to calculate kinetic energy ($\text{KE}$) for an object of mass $m$ moving at velocity $v$ is __________.

$$\frac{1}{2}mv^2$$

Gravitational potential energy ($\text{PE}$) is calculated using the formula __________.

$$mgh$$

Energy stored in objects that are stretched or compressed is classified as __________ energy.

elastic (strain)

A machine in which the kinetic energy of a moving fluid is converted into mechanical power by impulses on blades or buckets around a wheel is called a __________.

turbine

Petroleum and natural gas are composed mainly of hydrocarbons, whereas coal consists mainly of __________ with some hydrocarbons.

carbon

Unlike wind and solar power, tidal energy is more __________, though it suffers from high setup costs and limited suitable locations.

predictable

Nuclear fission occurs when a heavy nucleus is bombarded by __________ and decomposes into two nuclei of equivalent size with a massive release of energy.

neutrons

When thermal expansion occurs across the states of matter, __________ expand the most and solids expand the least.

gases

Particles in a solid are very closely packed in a regular arrangement and only __________ about fixed positions.

vibrate

In a thermal power station where $100\,\text{J}$ of fuel energy yields $35\,\text{J}$ of electrical energy, steam cooling accounts for __________ of energy loss.

$$40\,\text{J}$$

In geothermal energy systems, thermal energy travels outward from the Earth's molten core through rock layers via __________ and conduction.

convection

Overhead cables are installed with deliberate __________ to allow them to contract and straighten without snapping in cold weather.

sagging

To accommodate thermal expansion safely, __________ are fixed at the ends of bridges.

rollers

Of aluminium, brass, copper, and iron, the material that undergoes the highest degree of thermal expansion is __________.

aluminium

In an electric iron thermostat, the bimetallic strip bends away to open the contacts when hot because copper expands __________ than iron.

more

If concrete slabs are laid tightly on a cold day without expansion gaps, rising temperatures on a hot day will cause the pavement to expand and __________.

crack