Cambridge International AS & A Level · 3 · structured
Explain the whole parachute journey
Drag, falling and terminal velocity · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- demanding
- Marks
- 9
- Topics
- 3
- Answer
- Complete
Answer both parts about contact friction and motion with air resistance.
- (a)
A box slides to the right over a rough horizontal surface. State the direction of the contact-friction force and explain what relative motion it opposes. The same box is then at rest: a small rightward push does not make it move. State the friction direction and explain why friction can act even though the box is stationary.
2 marks - (b)
Explain, using weight, drag and resultant force, a parachutist's motion from release to first terminal speed, immediately after the parachute opens, and at the new terminal speed. Sketch a downward-positive velocity–time graph and explain why terminal speed does not mean zero velocity.
7 marks
Ready to self-mark?Reveal the detailed answer guide
(a)
A box slides to the right over a rough horizontal surface. State the direction of the contact-friction force and explain what relative motion it opposes. The same box is then at rest: a small rightward push does not make it move. State the friction direction and explain why friction can act even though the box is stationary.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
Leftward sliding friction opposing relative rightward sliding (1).
- 2
Leftward static friction opposing the tendency to move despite zero actual velocity (1).
(b)
Explain, using weight, drag and resultant force, a parachutist's motion from release to first terminal speed, immediately after the parachute opens, and at the new terminal speed. Sketch a downward-positive velocity–time graph and explain why terminal speed does not mean zero velocity.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
At release drag≈0 and downward a≈g.
- 2
Increasing speed increases upward drag, reducing downward acceleration.
- 3
First terminal state has drag=weight, zero resultant and a=0 but v>0.
- 4
Opening makes drag greater than weight; acceleration is upward while motion remains downward.
- 5
Falling speed and drag decrease until a lower terminal state.
- 6
Sketch continuous positive velocity rising to a plateau, then falling to a lower plateau, with correct changing slopes.
Complete marking guidance
Use these worked steps alongside the part-by-part answers. They explain the method and mark allocation; they do not add extra marks.
- (a) Leftward sliding friction opposing relative rightward sliding (1).
- (a) Leftward static friction opposing the tendency to move despite zero actual velocity (1).
- (b) At release drag≈0 and downward a≈g.
- (b) Increasing speed increases upward drag, reducing downward acceleration.
- (b) First terminal state has drag=weight, zero resultant and a=0 but v>0.
- (b) Opening makes drag greater than weight; acceleration is upward while motion remains downward.
- (b) Falling speed and drag decrease until a lower terminal state.
- (b) Sketch continuous positive velocity rising to a plateau, then falling to a lower plateau, with correct changing slopes.
Private on this device