IB Physics

What is the unit watt in terms of SI base units?

• Js^–1

• m²kgs^–1

• m²kgs^–1

• Nms^–1

The diameter of a cylindrical metal rod is measured using a micrometer screw gauge. The diagram shows an enlargement of the scale on the micrometer screw gauge when taking the measurement. 
What is the cross-sectional area of the rod?

• 3.81mm² 
• 11.4mm² 
• 22.8mm² 
• 45.6mm² 

A mass is dropped from rest, and falls through a distance of 2.0 m in a vacuum. An observer records the time taken for the mass to fall through this distance using a manually operated stopwatch and repeats the measurements a further two times. The average result of these measured times, displayed in the table below, was used to determine a value for the acceleration of free fall. This was calculated to be 9.8 ms^–2.
Which statement best relates to the experiment? 

• The measurements are precise and accurate with no evidence of random errors. 
• The measurements are not accurate and not always recorded to the degree of precision of the measuring device but the calculated experimental result is accurate. 
• The measurements are not always recorded to the degree of precision of the measuring device but are accurate. Systematic errors may be present. 
• The range of results shows that there were random errors made but the calculated value is correct so the experiment was successful. 

Tags

NGSS.HS-PS2-1

Which of the following is a valid statement? 

• A measurement that is not precise can be accurate. 
• A measurement that is precise is always accurate. 
• A measurement that is not precise will always be inaccurate. 
• Repeated measurements will always increase accuracy and precision. 

The masses and weights of different objects are independently measured. The graph is a plot of weight versus mass that includes error bars.
These experimental results suggest that 

• the measurements show a significant systematic error but small random error. 
• the measurements show a significant random error but small systematic error. 
• the measurements are precise but not accurate. 
• the weight of an object is proportional to its mass. 

Tags

NGSS.HS-PS2-4

A student takes measurements of the current in a resistor of constant resistance and the potential difference (p.d.) across it. The readings are then used to plot a graph of current against p.d. There is a systematic error in the current readings.
How could this be identified from the graph? 

• At least one anomalous data point can be identified. 
• The data points are scattered about the straight line of best fit. 
• The graph is a curve, not a straight line. 
• The straight line graph does not pass through the origin. 

The diagram shows the stem of a Celsius thermometer, marked to show initial and final temperature values. 
What is the temperature change expressed to an appropriate number of significant figures? 

• 14°C
• 20.5°C
• 21°C
• 22.0°C

Tags

NGSS.MS-PS3-4

The number of heartbeats of a person at rest in one hour, to the nearest order of magnitude is 

• 10¹
• 10²
• 10³
• 10⁵

The diameter of a proton is of the order of magnitude of 

• 10^-12m
• 10^-15m
• 10^-18m
• 10^-21m

An ammeter has a zero offset error. This fault will affect 

• neither the precision nor the accuracy of the readings. 
• only the precision of the readings. 
• only the accuracy of the readings. 
• both the precision and the accuracy of the readings.