Practice IB Design Technology (First Exam 2027) Topic B3.3 Mechanical Systems Application and Selection with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for B3.3 Mechanical Systems Application and Selection and mirrors Paper 1, 2 style where relevant.
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A product development team is designing a simple mechanical device that uses gears, levers, and cams to perform basic tasks with minimal power input. To evaluate different mechanical system components, the team examines standard configurations that affect motion, force, and efficiency. Figures 1 to 3 show common mechanical systems used in such devices.
Figure 1 shows a simple gear train with three meshed spur gears mounted on parallel shafts.
Explain the role of the idler gear in Figure 1.
Figure 2 shows a class 1 lever with labeled positions for the fulcrum, effort, and load.
Using Figure 2, state which position (effort, load, or fulcrum) should be moved (and in which direction) to reduce the effort needed to lift the load.
Describe how a first-class lever (Figure 2) provides mechanical advantage, and give one real-life example of its use.
Figure 3 shows a cam and follower system where a rotating cam drives a vertical follower up and down.
Identify two ways a cam and follower system (Figure 3) can be modified to change the motion of the follower.
Using Figures 1 and 3, compare how gear systems and cam systems affect motion in mechanical designs.
Pharos Optics builds the gear drive shown in Figure 1, which slowly rotates the heavy lens of a lighthouse. A motor turns the drive gear, which has 20 teeth, at 60 rpm. The drive gear meshes with the larger driven gear, which has 80 teeth and turns the lens turntable. The lens must rotate slowly and steadily but needs a large turning force to overcome its weight and friction.
Figure 1: The lighthouse lens gear drive, showing the meshing gears behind a glass guard
State what happens to the torque when a small gear drives a larger gear.
Outline why the meshing gears must be lubricated.
Apply the gear ratio to determine the gear ratio, the rotational speed of the driven gear, and the effect on torque.
State the name given to the smaller of two meshing gears.
In which class of lever is the fulcrum located between the effort and the load?
What is the purpose of this cam-follower mechanism?
Which of the following is NOT a purpose of cams and followers?