# Exercises – Conversion of the Unit of Speed, Density and Pressure

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1. Complete the following unit conversion of speed.
1. 90 kmh-1 = __________ ms-1
2. 110 kmh-1 = __________ ms-1
3. 1.3 ms-1 = __________ kmh-1
4. 8.12 ms-1 = __________ kmh-1
Answer:
a. $90km h −1 = 90km 1h = 90× 10 3 m 60×60s =25m s −1$ b. $110km h −1 = 110km 1h = 110× 10 3 m 60×60s =30.6m s −1$ c. $1.3m s −1 = 1.3m 1s = 1.3km 1000 1h 60×60 = 1.3km 1000 × 60×60 1h =4.68km h −1$ d. $8.12m s −1 = 8.12m 1s = 8.12km 1000 1h 60×60 = 8.12km 1000 × 60×60 1h =29.2km h −1$
2. Complete the following unit conversion of density and pressure.
1. 760 kgm-3 = __________ gcm-3
2. 12000 kgm-3 = __________ gcm-3
3. 5.1 gcm-3 = __________ kgm-3
4. 3600 Nm-2 = __________ Ncm-2
5. 12x106  Nm-2 = __________ Ncm-2
6. 1.5x103 Nm-2= __________ Ncm-2
7. 3.16x10-5 Ncm-2= __________ Nm-2
8. 7.1x10-3 Ncm-2 = __________ Nm-2
Answer:
a. $760kg m −3 = 760kg 1 m 3 = 760× 10 3 g 1000000c m 3 =0.76gc m −3$ b. $12000kg m −3 = 12000kg 1 m 3 = 12000× 10 3 g 1000000c m 3 =12gc m −3$ c. $5.1gc m −3 = 5.1g 1c m 3 = 5.1 1000 kg 1 m 3 1000000 =5100kg m −3$ d. $3600N m −2 = 3600N 1 m 2 = 3600N 10000c m 2 =0.36Nc m −2$ e. $12× 10 6 N m −2 = 12× 10 6 N 1 m 2 = 12× 10 6 N 10000c m 2 =12× 10 2 Nc m −2$ f. $1.5× 10 3 N m −2 = 1.5× 10 3 N 1 m 2 = 1.5× 10 3 N 10000c m 2 =0.15Nc m −2$ g. $3.16× 10 −5 Nc m −2 = 3.16× 10 −5 N 1c m 2 = 3.16× 10 −5 N 1 m 2 10000 =0.316N m −2$ h. $7.1× 10 −3 Nc m −2 = 7.1× 10 −3 N 1c m 2 = 7.1× 10 −3 N 1 m 2 10000 =71N m −2$