Second term physics

What is motion?

This is the study of change in position of an object in relation to its surrounding.

Define the term distance (x)

This is the length of the complete path taken by an object. The SI unit for distance is meter (m)

Define the term displacement (s)

This is the distance traveled in a particular direction measured in a straight line. The SI unit for displacement is meter (m)

When is the displacement zero?

The displacement is zero if you start at one end and return to that end

Define the term speed (v)

This is the rate of change of distance moved by an object

Define the term average speed

This is the total distance traveled divided by the total time

Define the term instantaneous speed

This is the speed of an object at a particular instant

Define the term velocity (v)

This is the rate of change of displacement of an object

How is the average velocity found?

This is found by dividing the total displacement by the total time

Define the term Acceleration

This is the rate of change of Velocity of an object

What does a negative value for Acceleration indicate?

A deceleration

What are the graphs used to represent the motion of objects?

Displacement and Velocity time graph

What is a displacement time graph?

This is the graph of motion that shows a plot of displacement on the y-axis and time on the x-axis.

What can be obtained from a displacement time graph (dtg)?

1. The motion of the object over a period of time by observing the shape of the graph.

2. The Velocity of the object by calculating the gradient or slope.

What is a Velocity time graph?

This is the graph of motion that shows a plot of velocity on the y-axis and time on the x-axis.

What is observed when a Velocity time graph is plotted?

How the Velocity of an object changes over time

What can be obtained from a Velocity time graph?

1. The motion of the object by observing the shape of the graph.

2. The Acceleration of the object by calculating the slope of the Velocity time graph (vtg).

3. The distance travelled from the Velocity time graph by calculating the area under the graph.

Define the term momentum

This is defined as the product of mass and Velocity of an object

What does the law of conservation of linear momentum state?

This states that for an isolated or closed system of colliding objects, the total momentum before collision is equal to the total momentum after collision.

What are the types of collisions?

Elastic and inelastic collision

What is an elastic collision?

This is a type of collision in which both the total momentum and total kinetic energy are conserved. In this type of collision, the objects collide and separate after collision.

What is an inelastic collision?

This is a type of collision in which only the total momentum is conserved since some of the initial kinetic energy is converted to other forms of energy. In this type of collision, the objects collide and stick together therefore moving with a common Velocity, V.

What are Sir Issac Newton’s three laws of motion?

1. The law of inertia (First Law)

2. The second law

3. The law of action-reaction (Third law)

What does the law of inertia state?

This states that if an object is at rest it will stay at rest, but if in motion, it will continue moving in a straight line at constant velocity unless acted upon by a net force (The net effect of multiple forces acting on a system).

What does the second law state?

This states that the net force of an object is directly proportional to its rate of change of momentum.

What does the law of action-reaction state?

This states that if body A exerts a force on body B then body B will exert an equal but oppositely directed force on body A

What is energy?

This is the ability to do work. Its SI unit is the Joule (J).

What are the 2 main types of energy?

Kinetic and Potential energy

What is kinetic energy (K^E)?

This is the energy a body has due to it’s motion.

What is the formula for kinetic energy?

KE= ½ mv²

What is Potential energy (P^E)?

This is the stored energy a body has due to its position or state.

What are the forms of Potential energy?

1. Gravitational Potential Energy

2. Elastic Potential Energy

3. Electrical Potential Energy

4. Chemical Potential Energy

What is gravitational potential energy (GPE)?

This is the stored energy a body has due to its position within a gravitational field.

What is the formula to find the gravitational potential energy?

GPE=mgh

What does the law of conservation of energy state?

This states that energy can neither be created nor destroyed, however it can be converted from one form to another.

What is mechanical energy?

This is the total amount of potential and kinetic energy of a system.

What is the formula for mechanical energy?

ΔKE=ΔGPE

In terms of mechanical energy, what is the formula to find the velocity?

V= 2gh

In terms of mechanical energy, what is the formula to find the height?

h= V²/2g

What is work?

This is the product of force and displacement. When work is done energy is always converted.

What is the formula for work?

W= Fs

What is power?

This is the rate at which work is done, or energy is converted.

What is the formula for power?

P= W/t or E/t

Define the term efficiency

This is the amount of input energy that is converted to useful output energy. The efficiency of a device cannot exceed 100%. However, for most practical devices the efficiency is usually less than 100%

What is the formula used to calculate efficiency?

Useful output energy/input energy * 100%

What is the joule?

This is the unit of energy equivalent to the work done or energy converted when a force of 1N causes an object to move a distance of 1m in the direction of the force.

What is pressure?

This is the force exerted per unit area.

Define the term hydrostatics

This is the study of the pressure exerted by a fluid on any object immersed in the fluid.

What is a fluid?

This is any medium that takes the shape of its container. Liquids and gases are examples of fluids.

Define the term atmospheric pressure

This is the pressure exerted by the Earth’s atmosphere. Atmospheric pressure decreases with altitude.

What is the value of atmospheric pressure?

100,000 Pa or 100 KPa at sea level.

What is the formula to find the pressure due to a fluid

P= ρgh

What is the unit of density in a fluid

kg/m³

What is the formula for calculating the change in pressure due to a fluid?

ΔP= ρgΔh

What does Archimedes’ principle state?

This states that for an object partially or fully submerged in a fluid (liquid or gas), the upthrust force on the object is equal to the weight of the volume of fluid displaced.

What is the formula to find the upthrust if the object floats in the fluid?

U= W_f =W_o

What is the formula to find the upthrust if the object sinks in the fluid?

U= U<W

What is the formula to find the upthrust if the object rises in the fluid?

U>w

Initially, what did scientists claim heat to be?

This was claimed to be a fluid-like substance called caloric. Caloric was able to move from a hot object to a cold object. This idea was known as the caloric theory.

How did Count Rumford contribute to the caloric theory?

While boring cannons he realized that the metal got hotter the more he drilled.

How did James Joule contribute to the caloric theory?

He conducted a puddle-wheel experiment to demonstrate that mechanical energy can be converted to heat.

What was gained from Joule’s experiment?

It was shown that mechanical energy can be converted to an equivalent amount of heat. Therefore, heat is a form of energy because it is converted based on (from) another forms of energy.

What does the kinetic theory state?

This states that matter is comprised of tiny particles in constant random motion.

What is temperature (T)?

This is a measure of the average kinetic energy of the molecules of a substance. The SI unit is the kelvin (K)

What is heat/ thermal energy (E_H)?

This is a measure of the total internal (both kinetic and potential) energy of the molecules of a substance.

In which direction is heat/thermal energy always transferred?

This is always transferred in the direction from the hotter object towards the colder object.

What is heat transfer?

This is the transference of heat from a hotter object to a colder object until thermal equilibrium is achieved.

What is the evidence of the kinetic theory?

1. Diffusion- The movement of particles from a region of higher concentration to a region of lower concentration until evenly distributed.

2. Osmosis- The diffusion of water molecules across a semi-permeable membrane

3. Brownian motion- The random movement of particles due to collisions with the molecules of the medium

What is a thermometer?

This is a device used to measure the temperature of substances.

What is a thermometric property?

This refers to the substance present in a thermometer that has a property that changes in response to a change in temperature.

What are some examples of thermometric properties?

1. The volume of the trapped liquid

2. The potential difference

3. The resistance

4. The pressure of the trapped gas

What are the types of thermometers?

1. Liquid in glass thermometer

2. Thermocouple

3. Resistance thermometer

4. Infrared thermometer

5. Constant-volume gas thermometer

What are the types of liquid in glass thermometers?

Clinical thermometer and laboratory thermometer

What is a clinical thermometer?

This is a thermometer used to measure the temperature of the human body. It has a limited range of 35°C-44°C. It has a constriction above the bulb which delays the mercury flowing back into the bulb of the thermometer.

What are the key design features of a clinical thermometer and state their function

1. It has a limited range of temperature (35°C-44°C)- To measure human body temperature

2. It has a constriction in the bore- It prevents the mercury from flowing into the bulb of the thermometer.

What is a laboratory thermometer?

This is a thermometer used to measure temperature during specific experiments. It ranges from -20°C to 100°C.

What are the key design features of a laboratory thermometer and state their function

1. It has a narrow range of temperature- To measure temperature in the laboratory.

2. It has a narrow bore- To ensure liquid is able to flow up the thermometer by capillary action.

What is a thermocouple?

This is a thermometer constructed from two dissimilar metals joined at two junctions. Whenever there is a temperature difference across the junctions a potential difference (p.d) is produced.

What are the key design features of a thermocouple and state their function

1. Two dissimilar metals- To measure very high and very low temperatures (-200°C to 1500°C.)

2. Junction of small mass- To measure rapidly changing temperatures

How do thermocouples remotely measure temperature?

They transmit electrical signals via a transmitter.

What are the temperature scales?

The Celsius scale and the kelvin scale

What is the Celsius scale?

This is a linear temperature scale consisting of 100 evenly spaced divisions each measuring 1 Celsius degree.

What are the 2 fixed points on the Celsius scale?

The upper fixed point and the lower fixed point

What is the upper fixed point?

This is the temperature at which pure water boils at sea level/ atmospheric pressure (100°C.)

What is the lower fixed point?

This is the temperature at which pure ice melts (0°C.)

What is the kelvin scale?

This temperature scale eliminates the concept of “negative temperature “. The lowest possible temperature on this scale is (0K). The value is known as “Absolute zero”.

What is the value of absolute zero (0K) in 0°C?

-273°C

What is absolute zero?

This is the lowest possible temperature at which the molecules of a substance has zero kinetic energy

What is the formula used to convert temperature in kelvin to 0°C?

θ/°C= T/K - 273

What is the formula used to convert temperature in celcius to temperature in kelvin?

T/K= θ/°C + 273