required practicals Flashcards
Describe a practical to investigate the relationship between the force and the extension of a spring.
force and extension relationship:
1) set up a clamp stand with two clamps connected
2) place a heavy weight on the clamp stand to stop it from falling over
3) attach a metre ruler and a spring to the clamps, with the top of the spring at the 0 on the metre ruler (the metre ruler must be vertical otherwise inaccuracies)
4) read where the spring is unstretched
5) hang a 1N weight on the spring and record new length of spring
6) repeat adding 1N every time
7) calculate extension of each
- plot a graph of extension against weight
- if it curves, it has exceeded the limit of proportionality
Describe a practical to investigate the effect of varying the force on the acceleration of an object with a constant mass.
varying force, constant mass:
1) set up a toy car attached to a piece of string looped around a pulley attached to a 1N weight
2) draw chalk lines on the desk at equal intervals
3) hold the toy car at the starting point and let go
4) record how long it takes the car to pass each interval, and if too fast, record on slow motion on phone
5) repeat with different weights
Describe a practical to investigate the effect of varying the mass of an object on the acceleration produced by a constant force.
constant force, varying mass:
1) set up a toy car attached to a piece of string looped around a pulley attached to a 1N weight
2) draw chalk lines on the desk at equal intervals
3) attach a 200g mass to the toy car
4) hold the toy car at the starting point and let go
5) record how long it takes the car to pass each interval, and if too fast, record on slow motion on phone
6) repeat with different masses
Describe a practical to measure the wavelength, speed and frequency of water waves.
measuring water waves:
1) set up a ripple tank with a shallow tray of water
2) put a vibrating bar in connected to a power pack
3) above the water, put a lamp and below, white paper to produce an image of the waves on the paper
wavelength - place ruler on paper and freeze image of waves, measure 10 waves and then divide by 10
frequency - place timer by paper, count the number of waves passing a point in 10s and divide by 10
speed - frequency x wavelength
Describe a practical to measure the wavelength, speed and frequency of waves in a solid.
measuring waves in solid:
1) set up a string with one end attached to a vibration generator and the other end, a mass to keep the string taut
2) attach the vibration generator to a signal generator which allows the frequency to be changed of the vibration
3) turn on vibration generator and change the frequency to a standing wave (you can see clearly the wave), which is due to an effect called resonance
frequency - read on signal generator
wavelength - measure with a ruler
speed - frequency x wavelength
Describe a practical to measure the speed of sound waves in air.
speed of sound waves in air:
1) two people stand 500m apart
2) person 1 makes a noise, and when person 2 sees the noise being made, they start the timer
3) person 2 stops the timer when they hear the noise
4) distance / time
problems - everyone has a different reaction time, so reduce this by having multiple people and an average
- time between seeing and hearing is very short, so increase distance
Describe a practical to investigate the reflection of light by different types of surface and the refraction of light.
refraction of light:
1) draw a straight line on paper and draw the normal
2) place a glass block against the line so the normal is near the centre and draw around it
3) turn off all lights
4) turn on ray box so it hits the block at the normal, and keep moving until there is a reflected and transmitted ray
5) draw crosses along these rays and the incident ray
6) turn lights on and ray box off
7) remove glass block and draw lines along crosses, as well as connecting the incident ray and transmitted ray
8) measure the angle of incidence, reflection and refraction
9) repeat with different materials
- angles of incidence and reflection don’t change with material, but angle of refraction does
Describe a practical to investigate how much infrared is radiated by different substances.
infrared emitted:
- Leslie’s cubes measure how much infrared is emitted, and the four sides have a different surface (shiny metallic, white, shiny black, matte black)
1) fill Leslie’s cube with hot water
2) point an infrared detector at each of the surfaces and record the amount of infrared emitted
- must keep same distance between cube and detector
- if no infrared detector, use thermometer with bulb painted black, but resolution will be less
least - shiny metallic, white, shiny black, matte black - most
Describe a practical to investigate how much infrared is absorbed by different substances.
infrared absorbed:
1) have an infrared heater and on either sides two metal plates, one painted shiny metallic and the other matte black
2) use vaseline to attach drawing pin on other side and start timer
3) temp of metal plates will increase as they absorb infrared, so record time take for vaseline to melt and drawing pin to fall off
- matte black falls off first as they absorb more infrared
- infrared tends to be reflected off of shiny metallic surfaces
