Paper 2 required practicals

RP6 - Determine the correlation between the mass placed on a spring and the spring’s extension by measuring resultant spring lengths

Give sources of inaccuracy

1. Set up a clamp stand with two bosses securing two clamps onto the stand. Place a heavy weight onto the stand to stop it from falling over.

2. Attach a metre ruler vertically to one clamp and a spring to the other

3. The top of the spring must be on the zero point on the ruler

4. The bottom of the spring has a pointer that is horizontal, pointing towards the ruler

5. Measure and record the position of the pointer on the metre ruler - this is the unstretched length of the spring (with no force attached)

6. Hang a 1N weight onto the spring and measure and record the position of the pointer on the metre ruler

7. Continue to add weights increasing in 1N onto the spring and measure and record the position of the pointer on the metre ruler

8. Calculate the extension caused by each weight by subtracting the unstretched length to the stretched length (with the weight attached)

9. Plot a graph of the extension against the weight

There is a linear relationship between force applied and extension of spring, until the spring is stretched past its limit of proportionality.

force = spring constant x extension

This practical can be used to work out the weight of a mystery object by plotting a graph and seeing the extension caused by the object, and seeing what weight that correlates to.

Sources of inaccuracy:

• Parallax error

• Top of spring isn’t at 0 of ruler

• Spring may bounce or wobble, must allow it to settle

• Exceeds elastic limit

RP7 - Investigate the effect of varying the force on the acceleration of an object of constant mass.

1. Set up a toy car attached to a piece of string. The string must be looped around a pulley. The other end of the string must be connected to a 100g mass

The weight of the mass will provide the constant force acting on the toy car.

2. Set up a timer.

3. Hold the toy car at the starting point (0cm) and mark out a measured distance

4. Let go of the car and start the stopwatch

5. The weight provides a resultant force to the car, so the car will accelerate.

6. Stop the stopwatch and calculate acceleration using: (2 x distance) / time²

7. Repeat the experiment and change the masses on end of string

   1. However as mass of car and string must be constant, add the mass taken off back onto the car

However, as we are investigating the affect on a constant mass, the mass taken off needs to be added back onto the car so that the mass of the overall object (the toy car, the string and the weight on the end of the string) remains constant, despite the force changing (the weight on the end of the string).

We will find that (according to Newton’s second law) the force acting on the car is directly proportional to the acceleration of the car

RP7 - Investigate the effect of varying the mass of an object on the acceleration produced by a constant force.

1. Set up a toy car attached to a piece of string. The string must be looped around a pulley. The other end of the string must be connected to a 100g mass.

The weight of the mass will provide the constant force acting on the toy car.

2. Set up a timer and mark out a measured distance

3. Attach a mass to the toy car and hold it at the starting point

4. Release the car and start the stopwatch

5. Calculate the time taken to cover the distance and use the equation: acceleration = (2 x distance) / time²

6. Repeat the experiment increasing the mass added to the toy car

We will find that the acceleration of the object is inversely proportional to the mass of the object (according to Newton’s second law).

RP- 8

• Using a ripple tank to measure the wavelength, frequency and speed of water waves

A ripple tank is used to observe the features of water waves; it is a shallow tray of water with a vibrating bar in the middle

The bar is connected to a power pack and motor

When the bar vibrates, it creates waves across the surface of the water

Above the ripple tank is a lamp and below the ripple tank is a sheet of white paper

When the light shines through the water, it produces an image of the waves on the paper

• Record the waves using a mobile phone; allowing us to playback the recording or to freeze the image

• Measure the wavelength using a ruler on the paper

  • Freeze the image

  • Measure the distance between as many waves as possible, and divide by the number of waves to calculate the wavelength

• Measure the frequency using a stopwatch, and count the number of waves passing a point 10 seconds and divide by 10

  • Draw an arrow using a pen

  • Record the waves and timer and watch the video in slow motion

• Wave speed = frequency x wavelength

• Another way to calculate wave speed is to select a wave and measure the time it takes to move the length of the tank; calculate the speed by dividing the distance travelled by time taken

RP 8

• Measure the wavelength, frequency and speed of waves in a solid

• Place a string over a wooden bridge with one end attached to a vibration generator, and the other end attached to a mass which keeps it taught

• The vibration generator is connected to a signal generator which allows us to change the frequency of string oscillations

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• Produce a standing wave on the vibrating string by adjusting the frequency

• Measure the wavelength of the standing wave by measuring the length of the maximum number of waves and dividing by the number of waves, using a ruler (measured across two halves)

• Calculate wave speed by multiplying wavelength by frequency (read from signal generator)

RP 9

• Reflection and refraction

Ray box connected to power pack with a slit

• Place the glass block on a sheet of A3 paper and draw around it in pencil

• Mark a point halfway the length of the block and use a protractor to mark 90 degrees and draw the normal perpendicular to the block (draw the normal halfway into the block)

• Place the glass block back on the sheet

• Turn off the lights

• Switch on the ray box and direct a ray of light onto the point where the normal meets the glass block

• Mark the path of the incident ray and reflected ray with crosses

• Mark the path of the transmitted ray with crosses

• Switch off the ray box and remove the glass block

• Draw in the incident ray, reflected ray and transmitted ray

• Draw a line from the incident to the transmitted ray to show the pathway of the transmitted ray through the glass block

• Use a protractor to measure and record: angle of incidence, angle of reflection and angle of refraction (angle between the normal and the path of the transmitted ray through the block)

• Use a different material block

Sources of inaccuracy:

• Slit being too wide, so the width of the light ray is too wide, making it difficult to know where the centre of the light ray is to mark the pathway of light and measure the angles

Required practical 10

• Radiation and absorption

Radiation:

Leslie cube has different surfaces. Pour hot water in from a kettle

• Align the infrared detector with one side of the Leslie cube, a fixed distance away

  • If no infrared detector, use a thermometer with the bulb painted black

• Take the initial temperature of the surfaces using an infrared thermometer

• Fill the Leslie cube with hot water from a kettle and place the lid on to reduce heat loss by convection. Use a heat proof mat to reduce further heat loss to the table by conduction

• Take a new reading of the temperature of the surfaces

• Record temperature

Absorption:

• Infrared lamp

• Copper test tubes coloured with different materials (eg. colours, shiny, matt)

• Fill with water

• Connect bung to tube and place thermometer with bulb in water

• Expose to infrared radiation

• Record temperature of tubes every minute

• Compare final temperatures and rate of temperature increase

• Plot on graph