Required Practicals Paper 2

Question 1

Experiment for force on an spring

Answer 1

• Set up a clamp stand with a weight on the bottom, a clamp and boss and hang the spring from the clamp.
• Set up another clamp and a boss to fix a verticalmetre ruler alongside the spring so that the zero mark of the ruler is at the top of the spring
• Record the ruler reading tht is with the bottom of the spring and this is the intial unstretched length
• Hang a 1N weight onto the bottom of the spring and record the springs new length
• Calcualte the extension by doing extension = new length - intitial length
• Add further weights increasing by 1N each time
• For each new force/weight, find the new length of the spring and calculate the extension
• Plot a graph with changing extension and weight and there should be a directly proportional relationship due to hooke’s law

Question 2

Risk assessment for the experiment investigating the force on a spring

Answer 2

• Clamp stand may fall off desk and hurt someone’s feet
• To prevent this, use a clamp to fix the apparatus to the desk or put a heavy mass on the base of the clamp stand
• The spring could break, come loose and damage someone’s eyes - wear goggles as a precaution

Question 3

Experiment to investigate the acceleration of an object whilst varying force

Answer 3

• Attach a trolley to a piece of string with the other end of the string attached to a 100g mass and looped around a pulley
• The weight of the mass provides the force
• On the desk, draw chalk lines at regular intervals e.g. every 10cm
• Hold the trolley at the start and once you get go, immediately start the timer
• The car will accelerate due to the resultant force of the weight
• Get someone else to record the experiment so you can see the times accurately
• Repeat by changing the force by decreasing the mass e.g. by 20g each time but you have to keep the total mass constant so whatever mass you remove from the end of the string, you have to add the mass to the car
• As F = ma, we should find that the acceleration of the trolley is proportional to the mass on the other end of the string

Question 4

Experiment to investigate the acceleration of an object whilst varying mass

Answer 4

• Attach a trolley to a piece of string with the other end of the string attached to a 100g mass and looped around a pulley
• The weight of the mass provides the force
• On the desk, draw chalk lines at regular intervals e.g. every 10cm
• Hold the trolley at the start and once you get go, immediately start the timer
• The car will accelerate due to the resultant force of the weight
• Get someone else to record the experiment so you can see the times accurately
• Keep the force constant by using a 100g mass on the end of the string
• Repeat by attaching an extra mass to the trolley e.g. 200g
• As F=ma, we should find that as the mass of the car increases, the acceleration decreases as they are inversely proportional

Question 5

How to find the wavelength, wave speed and frequency using a ripple tank

Answer 5

• Set up a ripple tank with a shallow trough of water, a vibrating bar connected to a power pack, a light source above and a piece of paper below
• Record the waves using a mobile phone
• Wavelength - place a ruler on the paper and freeze the image of the waves. Measure the distance between one wave and 10 waves along (10 wavelength) then divide it by 10 to find 1 wavelength
• Frequency - record a 10s timer and the number of waves that pass a certin point then divide by 10
• Speed = use the wave speed equation or measure the time it takes 1 wave to travel the length of the ripple tank and use speed = distance/time

Question 6

How to find the wavelength, wave speed and frequency in a solid

Answer 6

• Attach an elastic piece of string to a vibration generator going into a signal generator and attach the other end to a retort stand with a weight on it so it doesn’t fall
• At certain frequencies, a standing wave pattern will be produced
• Wavelength - measure the whole string using a ruler and divide by the number of half wavelengthsand times by 2
• Frequency - can be read from the signal generator
• Wave speed - use the wave speed equation

Question 7

What happens if you increase the frequency of the string standing wave experiment

Answer 7

• At certain frequencies, there will be more half wavelengths
• However, the wavespeed will stay constant

Question 8

What does the wavespeed of the string depend on in the stading wave experiment

Answer 8

• The taughtness of the string
• the mass per cm

Question 9

How to investigate the reflection and refraction of light by different surfaces and substances

Answer 9

• Use a ray box(risk - hot), a lens and a slit to produce a narrow ray of light.
• Take a piece of A3 paper and draw a straight line down the centre using a ruler
• Draw the normal line at a right angle to this line
• Place a glass block against the first line so the normal is at the centre of it and draw around it
• Turn off all the lights and direct the ray block so it hits the block at the normal
• Adjust the ray box to change the angle of incidence until there is a reflected ray and a trasmitted ray
• Mark the paths of the incident, trasmitted and reflected ray with crosses
• Turn the light back on, switch off the ray box, remove the glass block and draw in the reflected, transmitted and incident rays
• Draw a line throught the box from the incident ray to the transmitted ray
• Measure the angles of reflecetion, incidence and refraction using a protractor
• Repeat with different materials

Question 10

Results of the light ray experiment

Answer 10

• The angles of incidence and reflection are the same for all materials as they don’t depend on the material
• However, the angle of refraction will be different with different materials

Question 11

How to investigate the amount of infrared radiation radiated by different surfaces

Answer 11

• Use a leslie cube which has 4 surfaces - a shiny metallic, white, shiny black and matt black surface
• First, fill the Leslie’s cube with hot water
• Point an infrared detector at each of the surfaces and record the infrared radiation they emit
• Control the distance between the surface and the detector for all surfaces
• We will find that the order of infrared emission for most to least is: matt black, shiny black, white and shiny metallic

Question 12

How to investigate the amount of infrared radiation absorbed by different surfaces

Answer 12

• Set up an infrared heater with two metal plates with one plate being shiny metallic and the other being matt black
• On the other side of the plates, use vaseline to attach a drawing pin to each
• switch on the heater and start a timer
• Record the time it takes for the drawing pins to fall off
• The drwaing pin on the matt black surface will fall off first because matt black is a better absorber of infrared radiation