Speed, velocity and accelerationIB MYP Sciences: Subtopic test

1. 1
   A cycling club in Nairobi times one of its riders over a straight 1200 m stretch of road. The rider takes 80 s to cover it.

   (a)

   What is the average speed of the rider?

   [1 mark]

   • A0.067 m/s
   • B15 m/s
   • C96 000 m/s
   • D1280 m/s

   (b)

   The rider's journey is described using four quantities. Which one is a vector quantity?

   [1 mark]

   • ADistance
   • BSpeed
   • CVelocity
   • DTime

   (c)

   The rider keeps the same average speed. Calculate the distance she travels in 2.0 minutes.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A sports car on a test track in Dubai starts from rest and accelerates in a straight line, reaching 27 m/s after 6.0 s.

   (a)

   What is the car's average acceleration during these 6.0 s?

   [1 mark]

   • A0.22 m/s²
   • B21 m/s²
   • C162 m/s²
   • D4.5 m/s²

   (b)

   The car then travels at a steady 27 m/s along a straight section for 10 s. What is its acceleration during this time?

   [1 mark]

   • A0 m/s²
   • B2.7 m/s²
   • C27 m/s²
   • D270 m/s²

   (c)

   A different car increases its velocity by 20 m/s with an acceleration of 2.5 m/s². Calculate the time this takes.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Aiko, a student in Osaka, investigates how the height of a ramp affects the speed of a toy car. She releases the car from rest at the top of the ramp and uses a stopwatch to time how long it takes to cross a 1.0 m flat track at the bottom. Each time is the mean of three runs. The mean times are 2.0 s for a ramp height of 5 cm, 1.4 s for 10 cm, 1.1 s for 15 cm and 1.0 s for 20 cm.

   (a)

   State a testable hypothesis for this investigation, giving a scientific reason, and identify the dependent variable.

   [3 marks]

   (b)

   Process the data: calculate the car's speed on the flat track for the 5 cm ramp, describe the trend in the results, and suggest one improvement to Aiko's method that would make her times more accurate.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A city council plans to cut the speed limit on a 3.0 km road beside a school from 50 km/h to 30 km/h. A local bus starts from rest at one end of the road, reaches 9.0 m/s after 12 s, completes the 3.0 km trip to the other end in 400 s, and then returns along the same road to its starting point.

   (a)

   Discuss the social and economic implications of lowering the speed limit on this road from 50 km/h to 30 km/h.

   [6 marks]

   (b)

   For the bus, calculate its acceleration over the first 12 s and its average speed on the trip to the other end. Then explain why its average velocity for the whole round trip (there and back to its starting point) is zero, although its average speed is not.

   [6 marks]

   Total for question 4: 12 marks

End of questions