1. 1
   A warehouse forklift applies a horizontal driving force of 900 N to a crate resting on a concrete floor, while friction between the crate and the floor acts against the direction of motion with a force of 300 N.

   (a)

   Why is force classed as a vector quantity?

   [1 mark]

   • ABecause it can only be measured in newtons
   • BBecause it only has magnitude
   • CBecause it has both magnitude and direction
   • DBecause it always acts vertically

   (b)

   What type of force is acting between the crate and the floor?

   [1 mark]

   • AFrictional force
   • BGravitational force
   • CElectrostatic force
   • DMagnetic force

   (c)

   Calculate the resultant force acting on the crate, stating its direction.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A skydiver jumps from an aircraft and falls through the air before opening her parachute. As her speed increases, the air resistance acting on her increases until it becomes equal in size to her weight.

   (a)

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

   [1 mark]

   • AEqual to her weight, acting downwards
   • BZero
   • CEqual to twice her weight, acting upwards
   • DIncreasing steadily

   (b)

   What happens to the skydiver's acceleration once she reaches terminal velocity?

   [1 mark]

   • AIt reverses direction
   • BIt increases rapidly
   • CIt becomes zero and she falls at a constant velocity
   • DIt stays the same as at the start of the fall

   (c)

   Explain why the skydiver reaches a terminal velocity.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A driver travelling at 20 m/s on a wet road sees a hazard ahead. Her reaction time is 0.6 s before she applies the brakes, during which the car continues at a constant 20 m/s. Once the brakes are applied, the car decelerates uniformly and comes to rest after travelling a further 25 m.

   (a)

   Calculate the thinking distance travelled by the car before the driver applies the brakes.

   [3 marks]

   (b)

   Calculate the car's total stopping distance, and identify two factors present in this situation that would increase the stopping distance compared with the same car on a dry road with an alert driver, explaining how one of these factors has this effect.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A physiotherapist is testing a resistance spring used in rehabilitation equipment. She hangs known loads from the spring and measures its extension: 2 N produces 4 mm, 4 N produces 8 mm, 6 N produces 12 mm, and 8 N produces 20 mm.

   (a)

   Describe how these results show that the spring obeys Hooke's law up to a point, and explain what has happened to the spring at a load of 8 N.

   [6 marks]

   (b)

   Using ideas about elastic behaviour, explain what would happen to the spring's length if the 6 N load were removed, and how this would differ if the 8 N load were removed instead.

   [6 marks]

   Total for question 4: 12 marks

End of questions