P2 Required Practicals

Question 1

Describe the spring extension required practical

Answer 1

• attach a spring to a clamp stand with ruler vertical along side
• add 1N mass
• measure extension and record result
• repeat with masses between 1N and 10N

Question 2

What considerations should be made in the spring extension required practical?

Answer 2

• the extension is the total increase in length from the original length
• don’t add too many masses or the spring will reach its limit of proportionality and measurements won’t be able to be made
• careful for masses to not fall on experimenters feet (keeps masses at minimum for good range)

Question 3

Describe how to investigate the effect of varying force/mass on acceleration

Answer 3

• attach trolley to a pulley with hanging masses
• use a light gate or stopwatch to measure time once trolley is released
• move 1N masses from mass holder to trolley each time
  (if investigating mass don’t add masses back on to trolley)

Question 4

What considerations should be made in the force/mass/acceleration practical?

Answer 4

• when changing force, keep the mass of the system constant
• fast events result in timing errors so repeat and find a mean to reduce effect of random errors
• if accelerating force is too low or mass too high, frictional force will make measurements inaccurate

Question 5

Describe the ripple tank required practical

Answer 5

• time how long it takes for one wave to travel length of the tank
• calculate wave speed using speed = d/t
• frequency = count number of waves to pass a point in a second
• estimate wavelength by masking peak to peak distance
• use a stroboscope to make the same measurements and compare results

Question 6

What considerations should be made in the ripple tank practical?

Answer 6

• stroboscopes improve accuracy
• by projecting a shadow of waves onto a screen below stroboscope, flash speed can be adjusted to make waves appear stationary so measurements can be taken more accurately
• higher frequencies that can’t be counted can be calculated using frequency = speed / wavelength

Question 7

How would you investigate reflection and refraction?

Answer 7

• set up light box, single slit slide, glass block, boundary line and normal
• draw around semi circle glass block
• mark position of light ray at start, end and entrance and exit to block
• remove block and connect lines
• add normal lines
• repeat on different pieces of paper for different incident rays
• repeat with blocks of different transparent materials

Question 8

What considerations should be made in the reflection and refraction practical?

Answer 8

• keep light ray as narrow as possible
• incident needs to be exact centre of flat side of block
• too wide or off centre will lead to inaccurate results
• block should be removed before measuring angles
• if protractor doesn’t like line up it will create a zero error (no 0 reading when it should be)

Question 9

Describe how you would investigate how amount of infrared radiation absorbed or radiated depends on surface

Answer 9

• take four boiling tubes painted in different colours (matt black, gloss black, white and silver)
• pour hot water in to each tube
• measure and record starting temperature of each tube
• measure temperature of tube every minute for 10 minutes
• the tube that cools the fastest emits infrared energy the quickest

Question 10

What considerations should be made in the infrared required practical?

Answer 10

• boiling tubes need to be same temperature from start (or calculate percentage decrease)
• evaporation from surface of water can cause cooling too, effecting the results, so top of each tube should be blocked with cotton wool