OpenRevise

Flashcards · Maths · Ratio and Proportion

Speed, Distance, Time and Density

17 cards

  1. What is the formula for speed?

    Speed \(=\) distance \(\div\) time.

  2. How do you find distance from speed and time?

    Distance \(=\) speed \(\times\) time.

  3. How do you find time from distance and speed?

    Time \(=\) distance \(\div\) speed.

  4. How many hours is 30 minutes, 45 minutes and 20 minutes?

    0.5 hours, 0.75 hours and \(\dfrac{1}{3}\) hour.

  5. How many hours is 1 hour 12 minutes?

    1.2 hours, because \(12 \div 60 = 0.2\).

  6. What is the common mistake with 2 hours 30 minutes?

    Writing it as 2.3 hours. It is 2.5 hours.

  7. A car travels 150 km in 2 hours 30 minutes. What is its speed?

    \(150 \div 2.5 = 60\) km/h.

  8. How long does 90 km take at 60 km/h?

    1.5 hours, which is 1 hour 30 minutes.

  9. What is average speed?

    Total distance divided by total time.

  10. Why is the average of 30 km/h and 60 km/h not always 45 km/h?

    The time spent at each speed may differ. For equal distances the average speed is 40 km/h.

  11. What does the gradient of a distance-time graph show?

    The speed.

  12. What does a flat section of a distance-time graph mean?

    The object is stationary.

  13. What does a downward section of a distance-time graph mean?

    The object is returning towards the start.

  14. What is the formula for density?

    Density \(=\) mass \(\div\) volume.

  15. A metal has density 8 g/cm\(^3\). What is the mass of 25 cm\(^3\)?

    \(8 \times 25 = 200\) g.

  16. What is the formula for pressure (Higher tier)?

    Pressure \(=\) force \(\div\) area.

  17. How do you change 72 km/h to m/s (Higher tier)?

    Multiply by 1000 and divide by 3600, which gives 20 m/s.