Exam-style Questions: Forces, Moments and Pressure

 

  1. a) State two effects a force can have on an object.

    (2 marks)

    b) Name each of the forces labelled P, Q and R.

    Exam-style Questions

     

    (3 marks)

    c) Describe the motion of the submarine.

    Exam-style Questions

     

    (2 marks)

    d) If the forces on the cyclist are balanced then describe its motion.

    Exam-style Questions

     

    (1 mark)

    e) State two ways of reducing the drag forces on the bicycle.

    (2 marks)

    (Marks available: 10)

    Answer

     

    Answer outline and marking scheme for question: 1

    a) Change the objects shape, break the object, change the speed or direction of the objects motion.

    (2 marks)

    b) P = pushing force. Q = Weight / Gravitational force. R = Frictional force.

    (3 marks)

    c) Accelerating both up and forward.

    (2 marks)

    d) Balanced forces occur at a steady speed (and when stationary - less likely in this case).

    (1 mark)

    e) Oil wheels, Sit in a streamlined position, cycle downhill, use a smoother road.

    (2 marks)

    (Marks available: 10)

  2. a) An Ice Hockey player hits a 2kg puck with a force of 24N and it moves off with an initial acceleration of 12 m/s2.

    Exam-style Questions

     

    What could be done to make the puck move with higher acceleration?

    (2 marks)

    b) What force would be needed to give an acceleration of 9 m/s2?

    (2 marks)

    c) A sports car and a motorbike both have good acceleration.

    The car is mass 1200 kg and provides a driving force of 7200 N. What is its acceleration?

    (2 marks)

    d) The bike is mass 300 kg and provides a driving force of 2700 N. What is its acceleration?

    (2 marks)

    e) If the car crashes and the driver is not wearing a seatbelt he will go through the windscreen.

    Why is it wrong to say that he has been 'thrown forward'?

    (2 marks)

    (Marks available: 10)

    Answer

     

    Answer outline and marking scheme for question: 2

    a) Provide more force from the stick or reduce the mass of the puck.

    (2 marks)

    b) Provide more force from the stick or reduce the mass of the puck.

    Force = 2 x 9 = 18 N

    (2 marks)

    c) Acceleration = force / mass

    For the car: accel = 7200 N / 1200 kg = 6 m/s2.

    (2 marks)

    d) For the bike: accel = 2700 N / 300 kg = 9 m/s2.

    (2 marks)

    e) The driver continues forward because without the seat belt there is no force to stop him until he hits the windscreen.

    (2 marks)

    (Marks available: 10)

  3. a) An aid plane is flying over a remote part of Africa and it has to drop an aid package as there is no landing strip.

    Exam-style Questions

     

    There are two forces on the falling package - its weight and air resistance.

    What causes the weight?

    (1 mark)

    b) What causes the air resistance?

    (1 mark)

    c) A parachute opens as the package falls. How does the shape of the parachute help the drop?

    (2 marks)

    d) Which of the weight and air resistance is greater when the package first falls out of the plane?

    (1 mark)

    e) Which of the weight and air resistance is greater when the parachute on the package first opens?

    (2 marks)

    f) Describe a shape that would fall quickly through the air with low air resistance.

    (1 mark)

    g) Why does it make little difference if you fall out of a plane without a parachute at 700 m and at 7000 m?

    (2 marks)

    (Marks available: 10)

    Answer

     

    Answer outline and marking scheme for question: 3

    a) Weight is caused by the gravitational attraction of the object to earth.

    (1 mark)

    b) Friction with the air causes air resistance.

    (1 mark)

    c) The large area of the parachute creates a lot of air resistance, which slows the descent.

    (2 marks)

    d) At first the weight is greatest.

    (1 mark)

    e) When the parachute opens the air resistance is greatest.

    (2 marks)

    f) A rounded or pointed shape will cut through the air with minimum air resistance.

    (1 mark)

    g) When you fall you reach a terminal velocity. This is at a low height so the speed at which you hit the ground will be the same at both heights.

    (2 marks)

    (Marks available: 10)

  4. a) A car has to stop on a stretch of road. The overall stopping distance is made up of the thinking distance and the braking distance.

    What exactly is the driver doing during the thinking distance?

    (1 mark)

    b) What exactly is the driver doing during the braking distance?

    (1 mark)

    c) Names two factors that affect the thinking distance.

    (2 marks)

    d) State two weather conditions that would affect the stopping distance.

    (2 marks)

    e) Why is oil on the road a danger?

    (2 marks)

    f) Name two safety features that a car has.

    (2 marks)

    (Marks available: 10)

    Answer

     

    Answer outline and marking scheme for question: 4

    a) Driver is realising he must stop and moving his foot to the brake pedal.

    (1 mark)

    b) Driver is pressing the brake pedal.

    (1 mark)

    c) Tiredness, alcohol, drugs, medication, distractions in the car, driver experience.

    (2 marks)

    d) Ice, snow, rain, sleet, hail.

    (2 marks)

    e) Lubricant, which reduces the friction between wheels and road.

    (2 marks)

    f) Crumple zones, seat belts, side impact bars, air bags.

    (2 marks)

    (Marks available: 10)

  5. The diagram shows a graph of velocity against time for the journey of a motorbike.

    Exam-style Questions

     

    a) Between what times was the bike stopped at a traffic light?

    (1 mark)

    b) Between what times was the bike overtaking?

    (1 mark)

    c) What was the fastest speed reached?

    (1 mark)

    d) For how long was the bike travelling at this speed?

    (1 mark)

    e) Between what two bits of time was the bike accelerating?

    (2 marks)

    f) At 10 seconds the bike began to slow. What was the deceleration?

    (2 marks)

    g) How fast had the bike travelled in the first 15 seconds?

    (2 marks)

    (Marks available: 10)

    Answer

     

    Answer outline and marking scheme for question: 5

    a) Between 15 and 25 s

    (1 mark)

    b) Between 40 and 45 s

    (1 mark)

    c) 17.5 m/s

    (1 mark)

    d) 5 seconds

    (1 mark)

    e) Between 25 and 30 s and between 35 and 40 s

    (2 marks)

    f) Deceleration = change in velocity / time

    deceleration = 10 / 5 = 2 m/s/s

    (2 marks)

    g) Distance travelled equals the area under the graph.

    Distance = (10 x 10) + (0.5 x 10 x 5) = 100 + 25 = 125 m

    (2 marks)

    (Marks available: 10)

  6. A transit van is leaking oil and drips every two seconds. It leaves a pattern along a road as shown in the diagram.

    Exam-style Questions

     

    a) Describe the motion of the van between S and T where the drips are equal distances apart.

    (1 mark)

    b) What is the velocity of the van between S and T?

    (2 marks)

    c) How is velocity different from speed?

    (1 mark)

    d) What is the velocity of the van between P and Q?

    (1 mark)

    e) Using earlier answers and the diagram, calculate the acceleration of the van.

    (3 marks)

    f) If the engine cut out and the brake was not applied state what would happen to the van and why.

    (2 marks)

    (Marks available: 10)

    Answer

     

    Answer outline and marking scheme for question: 6

    a) A steady speed.

    (1 mark)

    b) Velocity = displacement / time

    velocity = 42 m / 6 s = 7 m/s

    (2 marks)

    c) Velocity is the speed in a specified direction.

    (1 mark)

    d) Vel = 24 / 6 = 4 m/s

    (1 mark)

    e) Acceleration = change in vel / time

    The time between the start of PQ to the start of ST is 6 spaces, which is 12 seconds.

    Acceleration = (7 - 4) / 12 = 0.25 m/s/s

    (3 marks)

    The van would decelerate to a stop because of friction.

    (2 marks)

    (Marks available: 10)