1. 1
   An engineering laboratory uses a tall drop-tower to release test components in free fall, studying the impact forces produced and tracking velocity against time as each component falls through the air.

   (a)

   On a velocity-time graph of a falling component, what does the gradient of the line represent?

   [1 mark]

   • Adistance travelled
   • Bacceleration
   • Cspeed
   • Dmomentum

   (b)

   Which value is closest to the acceleration of free fall near the Earth's surface, assuming air resistance is negligible?

   [1 mark]

   • A9.8 m/s²
   • B0.98 m/s²
   • C98 m/s²
   • D9.8 m/s

   (c)

   A component falls from rest with a constant acceleration of 9.8 m/s² for 2 s before the drop-tower's brake engages. Its velocity-time graph over this interval is a straight line through the origin. Calculate the distance the component falls in this time using the area under the graph.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A skydiver jumps from a plane and free-falls before opening her parachute, eventually reaching terminal velocity.

   (a)

   What is the resultant force acting on the skydiver once she reaches terminal velocity?

   [1 mark]

   • Aincreasing steadily
   • Bequal to her weight, acting downward
   • Cequal to her weight, acting upward
   • Dzero

   (b)

   What happens to the shape of the skydiver's velocity-time graph as she approaches terminal velocity?

   [1 mark]

   • Ait becomes steeper
   • Bit curves back down to zero
   • Cit becomes a horizontal (flat) line
   • Dit becomes a vertical line

   (c)

   Before reaching terminal velocity, the skydiver's velocity increases from 40 m/s to 50 m/s over 5 s. Calculate her acceleration during this interval.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Atmospheric scientists studying weather patterns investigate why a falling raindrop reaches a constant maximum (terminal) speed before it hits the ground, which is important for modelling rainfall in weather forecasts.

   (a)

   Explain, in terms of forces, why a raindrop reaches terminal velocity as it falls.

   [3 marks]

   (b)

   Describe the shape of a velocity-time graph for the raindrop from the moment it begins to fall (from rest) until it reaches terminal velocity, and explain what each feature of the graph represents in terms of the changing forces acting on it.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A university physics department repeats a historic experiment: dropping a feather and a hammer inside a large vacuum chamber (as first demonstrated on the Moon by Apollo astronauts) to show that, without air resistance, all objects fall with the same acceleration, then compares this with the same objects dropped in normal air outside the chamber.

   (a)

   Explain why, inside the vacuum chamber, the feather and the hammer fall with the same acceleration and reach the ground at the same time, but outside the chamber in normal air the hammer falls much faster than the feather, referring to the forces acting on each object.

   [6 marks]

   (b)

   Both objects are then dropped in air from a height of 5 m above the ground, from rest. Using $v^2 - u^2 = 2as$, estimate the impact speed of the hammer just before it hits the ground, assuming it experiences negligible air resistance and accelerates at 9.8 m/s² for the whole fall, and evaluate whether this same equation could be used reliably to estimate the feather's impact speed in air.

   [6 marks]

   Total for question 4: 12 marks

End of questions