9L Pressure and Moments ILU Level 3 4 5 6 7 no of qus 1 1 1 1 17 Level 3 1 Five people take it in turns to sit on a see-saw The table gives the weight of each person person weight, in N Jack 510 Ellie 540 Rosie 490 Maggy 540 Andy 560 (a) Andy sits at one end, but there is nobody on the other end Andy sits on the see-saw In which direction does his end of the see-saw move? (b) Which two people in the table above could make the see-saw balance? and 1
Use information in the table to help you answer parts (c) and (d) (c) Rosie sits on end A, and Jack sits on end B They lift their feet What happens to each end of the see-saw? Write up or down in the boxes under Rosie and Jack (d) Ellie sits on end A, and another of the group sits on end B Ellie's end stays down Who could be on end B? Maximum 4 marks 2
Level4 2 Tom tries on four types of footwear in a sports shop ski boot trainer ice skate walking boot (a) (i) When Tom tries on the footwear, which one sinks into the carpet the most? (ii) When Tom tries on the footwear, what is the same for each type of footwear? Tick the correct box the area of the footwear Tom s weight on the footwear the material of the footwear the weight of the footwear 3
(b) The drawing below shows a snowshoe snowshoe How do snowshoes help people to walk in deep snow? (c) Choose the correct word from the list to complete the sentence below air resistance friction gravity magnetism When Tom is ice skating the force of between the skate and the ice is less than when he is walking on a carpet Maximum 4 marks 4
Level5 3 The drawing below shows a cardboard scale called an EasyWeigh It can be used to estimate the mass of letters letter EasyWeigh pivot (a) Clare put a letter in the 20 g slot The scale tipped as shown below letter 100 g 40 g 20 g pivot She then put the same letter in the 40 g slot The scale did not tip (i) What do these results tell you about the mass of Clare s letter? 5
(ii) What could Clare do to this cardboard scale to weigh her letter more accurately? (b) (i) Clare drew a short line to show where she thought she should cut a slot to weigh a 150 g letter She labelled the slot Y Y 100 g 40 g 20 g pivot Why could Clare not use a slot at Y to weigh a 150 g letter? (ii) Clare wanted to cut a slot to weigh a 70 g letter On the diagram above, draw a short line to show where the slot should be cut maximum 4 marks 6
Level6 4 The drawing shows a boy with a bow and arrow He is holding the arrow and pulling it back (a) Two horizontal forces act on the arrow These are the force exerted by the boy s hand and the force exerted by the string The arrow is not moving The boy pulls the arrow with a force of 150 N What is the size of the force exerted by the string on the arrow? N (b) When the boy lets go of the arrow, it starts to move forward Explain why it starts to move 7
(c) The arrow flies across a field and hits a target Two forces act on the arrow while it is in the air Air resistance acts in the opposite direction to the movement, and gravity acts downwards These two forces cannot balance each other, even when they are the same size Why is this? (d) The arrow has a sharp pointed end When the arrow hits the target, the sharp point exerts a very large pressure on the target Why does a sharp pointed end exert a larger pressure than a blunt end? Maximum 4 marks 8
Level 7 (a small selection) 5 The diagram below shows a container filled with a liquid piston A area 20 cm 2 pedal liquid piston B area 80 cm At each end of the container there is a piston Piston A has a smaller area than piston B 2 (a) (i) Rebekah pushes on the pedal This produces a force of 200 N on piston A Calculate the pressure that piston A exerts on the liquid Give the unit (ii) The liquid in the container exerts the same pressure on piston B Use this pressure to calculate the force on piston B N 2 marks 9
(b) Rebekah set up a different experiment as shown below She measured the volume of the liquid and the air in the cylinders before and after a 200 g load was added to the piston 200 g load 200 g load liquid air without load with load without load with load (i) When the loads were added to the pistons, the volume of the liquid did not change but the volume of the air decreased Explain why this happened (ii) The diagram on the opposite page represents the way the brake system of a car works The brake pedal pushes piston A Piston B pushes the brakes on If air bubbles get into the liquid, the brakes do not work properly Explain why Use the diagrams above to help you maximum 5 marks 10
6 A father makes a simple mobile for his young son He uses plastic animals as shown below (a) (i) The elephant weighs 02 N What is the turning moment produced by the elephant about point X? Give the unit (ii) What is the turning moment produced by the monkey about point X? (iii) What is the weight of the monkey? 2 marks N (b) What is the size of the tension (force) in string A? N maximum 5 marks 11
7 (a) The diagram below shows a car park barrier 01m pivot 15m barrier iron counterweight 50 N (i) Calculate the turning moment produced by the barrier about the pivot Give the unit (ii) The barrier is horizontal The weight of the barrier is balanced by an iron counterweight Calculate the downward force produced by the counterweight N (b) An electromagnet is placed beneath the iron counterweight as shown below 2 marks iron counterweight battery electromagnet iron core When the switch is closed the barrier rises Explain how the electromagnet can be used to raise the barrier 2 marks maximum 5 marks 12
8 The diagram shows a crane lifting a load The counterweight and the load are balanced arm counterweight pivot load (a) The load is moved away from the pivot, to the right (i) What happens to the turning moment produced by the load? (ii) What should happen to the counterweight to keep the arm balanced? 13
(b) A load of 5000 N is placed 8 m from the pivot 8 m counterweight arm 10 000 N pivot load 5000 N (i) What is the turning moment of the load? Give the unit (ii) How far from the pivot must the 10000 N counter weight be placed in order to balance the load? m (iii) The counterweight is placed 3 m from the pivot What load could now be balanced 8 m from the pivot? N 2 marks Maximum 6 marks 14
9 The diagram shows a simple tool for punching holes in a leather belt pivot steel peg lightweight handle base hole in base piece of leather force applied not to scale When the handle is pressed down, the steel peg presses down on the piece of leather If the force is large enough, the peg punches through the leather, making a hole The diagram below shows the force applied to the handle pivot 4 cm 10 cm steel peg 50 N not to scale (a) Calculate the moment (turning effect) of the 50 N force applied to the handle Give the units (b) This moment makes the steel peg press down on the leather Calculate the force with which the steel peg presses down on the leather N 2 marks 15
(c) The next time the punch is used, the steel peg presses down on the leather with a force of 150 N (i) The area of the end of the steel peg is 01 cm2 What is the pressure of the steel peg on the leather? Give the units (ii) The pressure is too small, and the punch does not go through the leather How could you change the design of the punch to make it work using the same force on the handle? 2 marks Maximum 6 marks 16