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igcse-cambridge-physics-solution

Change in Momentum

All moving objects have momentum. Forces can cause changes in momentum. The total momentum in a collision or explosion is conserved and stays the same. Car safety features absorb energy involved in a crash they slow down the collision thus reducing the force of impact.

Demo

In this tutorial you will learn how to calculate the change in momentum and the affect it has on impact forces.

The equation is written like this:

$F = { mv \unicode{x2013} mu \over \text{t}}$

Chilled practice question

Calculate the force acting if there is a change in momentum from zero to 168 Kgm/s for 7 s.

Frozen practice question

A 50 kg gymnast is thrown in the air and travels at 5 m/s. The contact time to throw the gymnast is 0.5 seconds. Calculate the force acting on the gymnast.

Science in context

.All moving objects have momentum. Forces can cause changes in momentum. The total momentum in a collision or explosion is conserved and stays the same. Car safety features absorb energy involved in a crash they slow down the collision thus reducing the force of impact.

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Transformers

A transformer is an piece of electrical apparatus which will increase or decrease the voltage in an alternating current. It can be designed to “step up” or “step down” voltages and is based on the magnetic induction principle.

Demo

In this tutorial you will learn how to calculate voltages in step up and step down transformers.

The equation is written like this:

${ \text V_{1} \; \text / \; \text V_{2} \; \text = \; \text N_{1} \; \text / \; \text N_{2} \;}$

Chilled practice question

A transformer has 300 turns on its primary coil and 100 turns on it secondary coil. What voltage is induced in the secondary coil if the primary voltage is 96 V ?

Frozen practice question

A transformer has 320 turns on the primary coil and 800 turns on the secondary coil. Find the voltage across the primary coil when the voltage across the secondary coil is 1320 V.

Science in context

A transformer is an piece of electrical apparatus which will increase or decrease the voltage in an alternating current. It can be designed to “step up” or “step down” voltages and is based on the magnetic induction principle.When a voltage is introduced to one coil, called the primary coil it magnetizes its core which is made from iron which induces a voltage in the secondary coil.

Millie’s Master Methods

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Magnification

The magnification can be calculated if you know the actual size of the object and its image size.

Demo

In this tutorial you will learn how to calculate the magnification of objects in given examples.

Note-Some mobile devices may require you to tap full screen during playback to view video content.

The equation is written like this:

Magnification = image height / object height

Chilled practice question

Copy out the question and attempt to calculate the answer before watching the solution. Write down the equation and show all of your working, remember to add the units to your answer, this routine will guarantee you maximum marks in an exam. Mark your solution and correct if needed.

Calculate an objects magnification if the image height is 70 mm and the object height is 28 mm.

Frozen practice question

Copy out the question and attempt to calculate the answer before watching the solution. Write down the equation and show all of your working, remember to add the units to your answer, this routine will guarantee you maximum marks in an exam. Mark your solution and correct if needed.

Calculate the image height if an object height is 25 mm and the magnification is 3.5.

Science in context

The magnification can be calculated if you know the actual size of the object and its image size.

Millie’s Master Methods

The Fridge Physics Store

Pressure in Fluids

Fluid pressure is exerted on the surface of an object in a liquid. This pressure causes upthrust . An object placed in a liquid will begin to sink. As it sinks, the liquid pressure on it increases and so the upthrust increases.

Demo

In this tutorial you will learn how to calculate the pressure on an object in a fluid at a known depth.

The equation is written like this:

$P = { \text h \; \text x \; \text p \; \text x \; \text g}$

Chilled practice question

Calculate the pressure 180 m below the surface of sea water. The density of sea water is 1025 Kg/m3. Use Gravity as 9.8 N/kg.

Frozen practice question

Calculate the density of a liquid if the pressure exerted is 5880 Pa at a depth of 75 cm, take the Gravitational field strength of the Earth to be 9.8 N/Kg.

Science in context

Fluid pressure is exerted on the surface of an object in a liquid. This pressure causes upthrust. An object placed in a liquid will begin to sink. As it sinks, the liquid pressure on it increases and so the upthrust increases.

Millie’s Master Methods

The Fridge Physics Store

Acceleration

Acceleration is how quickly the velocity is changing whether it be speed, direction or both. Acceleration is a measure of how quickly the velocity of an object is changing.

Demo

In this tutorial you will learn how to calculate the acceleration of a moving object.

The equation is written like this:

$a = { v \unicode{x2013} u \over \text{t}}$

Chilled practice question

Calculate the acceleration if the velocity increases from 4 m/s to 76 m/s in 8 s.

Frozen practice question

How long does it take for the velocity of a bus to increase from 12 m/s to 20 m/s if it is accelerating at 4 m/s2.

Science in context

Acceleration is how quickly the velocity is changing whether it be speed, direction or both.

Millie’s Master Methods

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Speed

Speed is how fast an object is moving in no given direction. Velocity is how fast an object is moving in a given direction. In physics, you can calculate the average speed by taking the total distance travelled and dividing it by the total time required to travel that distance.

Demo

In this tutorial you will learn how to calculate the speed of an object, velocity is speed with direction for example 20 m/s north.

The equation is written like this:

$S = { \text D / T}$

Chilled practice question

Calculate the speed of a car which travels 2000 m in 400 s.

Frozen practice question

How long does it take a car to travel 360 m at 12 m/s ?

Science in context

Speed is how fast an object is moving in no given direction. Velocity is how fast an object is moving in a given direction.

Millie’s Master Methods

The Fridge Physics Store

Weight on the Moon

Weight is the force acting on an object due to gravity. The weight of an object is defined as the force of gravity on the object and can be calculated as the mass times the acceleration due to gravity.

Demo

In this tutorial you will learn how to calculate the weight of an object on the moon due to its force of gravity.

The equation is written like this:

${ \textit W} = {\text m \;} {\text x \;} {\text g}$

Chilled practice question

Copy out the question and attempt to calculate the answer before watching the solution. Write down the equation and show all of your working, remember to add the units to your answer, this routine will guarantee you maximum marks in an exam. Mark your solution and correct if needed.

Calculate the weight of a flag pole on the moon, it has a mass of 5 Kg.

Frozen practice question

Copy out the question and attempt to calculate the answer before watching the solution. Write down the equation and show all of your working, remember to add the units to your answer, this routine will guarantee you maximum marks in an exam. Mark your solution and correct if needed.

What is the mass of an oxygen cylinder on the moon if it has a weight of 4.8 N ?

Science in context

Weight is the force acting on an object due to gravity.

Millie’s Master Methods

The Fridge Physics Store

Weight on Earth

Weight is the force acting on an object due to gravity. The weight of an object can be defined as the force of gravity on the object. Since the weight is a force, its unit is the Newton.

Demo

In this tutorial you will learn how to calculate the weight of an object due to the force of the Earths gravity.

The equation is written like this:

${ \textit W} = {\text m \;} {\text x \;} {\text g}$

Chilled practice question

Calculate the weight of a bench on Earth which has a mass of 25 Kg.

Frozen practice question

Calculate the mass of an elephant if it has a weight of 60 KN on Earth.

Science in context

Weight is the force acting on an object due to gravity.

Millie’s Master Methods

The Fridge Physics Store

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