IB myp 4-5 physics – Practice Questions- All Topics
Topic :Forces and energy- Speed,Motion Graphs
Topic :Forces and energy– Weightage : 21 %
All Questions for Topic :Kinematic variables, types of motion, motion graphs, equations of motion
Question 1(8 marks)
The Shinkansen, commonly known as a bullet train, is a network of high-speed magnetic levitation trains in Japan. The Paragraph below explores how the trains were redesigned to minimize the loud booms produced when the trains entered a tunnel.
Japanese bullet trains were first designed in 1964. These trains use magnetic levitation. The repelling force between magnets is used to raise the train above the tracks. This reduces friction and allows the train to travel at very high speeds.
When in a tunnel, the fast speed and the bullet shape caused a layer of air to build up in front of a train. This caused a loud booming sound when the train exited the tunnel.
Scientists noticed that kingfisher birds did not disturb water when they dived into it due to the shape of their beaks. They redesigned the nose of the train by modelling it on a kingfisher’s beak.
The redesigned train cut through the air and reduced the build-up of layers of air in tunnels. This reduced the loud booming sound and increased the train’s efficiency.
Question a (3 marks)
The bullet train was redesigned to improve its performance. This redesign increased the maximum speed.
Select the correct term to complete the sentence. Justify your answer.
The thrust required for the redesigned train to move at a constant speed of $220 \mathrm{~km} \mathrm{~h}^{-1}$ is $\boxed{\rm{Select}}$ by ticking the thrust of the 1964 design.
- Greater than $()$
- Less than the $()$
- Same as $()$
Justification:
▶️Answer/Explanation
Ans:
Select: Less than $(\checkmark)$
Justification: The air resistance (drag force) will decrease and the forces are balanced thus have a contant speed.
The speed-time graph shows the motion of the 1964 train on its journey through a tunnel. Use the graph to calculate the length of the tunnel.
▶️Answer/Explanation
Ans:
$$\begin{aligned} & \text { Length of the tunnel }=\text { Area under the graph } \\ & \text { Length of the tunnel }=\frac{1}{2}(61+55) \times 62 \\ & \text { Length of the tunnel }=3596 \mathrm{~m} \\ & \text { Length of the tunnel }=3600 \mathrm{~m} (2 s.f) \end{aligned}$$
Question c (2 marks)
Draw a line on the graph to represent the journey of the redesigned train through the tunnel at the same initial speed.
▶️Answer/Explanation
Ans:
y intercept is the same and always above original line
