What is the unit of pressure and what is it equal to?

The pascal (Pa), equal to 1 N/m².

How close a measurement is to the true value.

How close repeated measurements are to each other.

What is a random error and how do you reduce it?

An unpredictable variation in readings. Repeat the readings and calculate a mean.

What is a systematic error? Give an example.

An error that shifts every reading the same way, such as a zero error on a balance.

How do you calculate a mean?

Add the readings (leaving out anomalies) and divide by the number of readings.

What should a line of best fit look like?

A smooth line or straight line close to most points, with points on both sides. Do not join the dots.

What is parallax error?

An error from reading a scale at an angle instead of with your eye level with the mark.

Measurement, units and uncertaintyIB MYP Physics: Flashcards

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Question

Name the five SI base units used in MYP Physics.

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Name the five SI base units used in MYP Physics.: Metre (m), kilogram (kg), second (s), ampere (A), kelvin (K).
What is the SI unit of force?: The newton (N).
What is the unit of pressure and what is it equal to?: The pascal (Pa), equal to 1 N/m².
What does the prefix kilo (k) mean?: × 1000 (10³).
What does the prefix micro (µ) mean?: × 10⁻⁶ (one millionth).
Convert 3.5 km to metres.: 3.5 × 1000 = 3500 m.
Define accuracy.: How close a measurement is to the true value.
Define precision.: How close repeated measurements are to each other.
What is a random error and how do you reduce it?: An unpredictable variation in readings. Repeat the readings and calculate a mean.
What is a systematic error? Give an example.: An error that shifts every reading the same way, such as a zero error on a balance.
How do you calculate a mean?: Add the readings (leaving out anomalies) and divide by the number of readings.
What should a line of best fit look like?: A smooth line or straight line close to most points, with points on both sides. Do not join the dots.
Which instrument measures the volume of a liquid most precisely?: A measuring cylinder.
What is parallax error?: An error from reading a scale at an angle instead of with your eye level with the mark.

Exam questions on Measurement, units and uncertainty

A student in Nairobi is helping to set up a school sports day. She measures the length of the running track as 24 000 mm and the mass of the winner's trophy as 2.5 kg.
State the SI unit, with its symbol, for force and for pressure.2 marks
Amara and Luis each time 20 swings of the same pendulum with a stopwatch. A laser timer shows the true time is 28.4 s. Amara's four readings are 31.2 s, 31.3 s, 31.2 s and 31.3 s. Luis's four readings are 27.1 s, 29.8 s, 28.0 s and 29.6 s.
Calculate the mean of Luis's four readings. Give your answer to one decimal place.2 marks
A class in Lisbon investigates how far a spring stretches when masses are hung from it. They hang masses from 100 g to 500 g, one at a time, and measure the length of the spring with a 30 cm ruler marked in millimetres. They will plot a graph of their results.
Identify the independent variable, the dependent variable and one control variable in this investigation.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).