Browse Compound units & rates

51 questions at your level

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Speed, distance and time

15 questions

LessonNot started
Amir drives 120 km at an average speed of 60 km/h, and then a further 120 km at an average speed of 40 km/h.

Meera says: "The average speed for the whole journey is 50 km/h, because the mean of 60 and 40 is 50."

(a) Show that the whole journey takes 5 hours.

(b) Work out the average speed for the whole journey, and explain why Meera is wrong.
●●●●●Level 55 marksStart
Two trains are 180180 km apart on the same line and travel towards each other, one at 7070 km/h and the other at 5050 km/h.

(a) Work out how long it takes until they meet. Give your answer in hours and minutes.

(b) Work out how far the faster train travels before they meet.
●●●●●Level 55 marksStart

Density and pressure

19 questions

LessonNot started
An alloy is made by mixing 150 cm³ of metal A, which has density 4.2 g/cm³, with 100 cm³ of metal B, which has density 6.7 g/cm³.

Work out the density of the alloy.
●●●●●Level 54 marksStart
An alloy is made by melting together 400400 g of metal PP and 270270 g of metal QQ.

Metal PP has density 88 g/cm³. Metal QQ has density 4.54.5 g/cm³.

Work out the density of the alloy. Give your answer correct to 3 significant figures.
●●●●●Level 54 marksStart

Converting compound units and rates of flow

19 questions

LessonNot started
A bottling machine fills 750750 ml bottles at a rate of 4040 bottles per minute.

(a) Work out the rate of the machine in litres per hour.

The machine must fill a vat order of 13 50013\,500 litres.

(b) Work out how long this takes. Give your answer in hours and minutes.
●●●●●Level 55 marksStart