SIMPLE MACHINE

1. Which pair of devices does not use the principle of lever?

A Screw and ladderB Fishing rod and pliersC Nutcracker and paper cutterD Wheel-barrow and bottle opener

PMR 2008

2. Which crowbar uses the least effort to pull out the nail?

PMR 2008

3 Diagram 14 shows the position of a worker’s hands lifting sand using a spade.

A Move both hand to P.B Move the right hand to Q and the left hand to S.C Move the left hand to S without changing the position of the right hand.D Move the left hand to R without changing the position of the right hand.

PMR 2007

4 Diagram 15 shows a nail being pulled out uing tools, P and Q.

Which of the following statements is correct about the effort that was used?

A P needs less effort than Q to pull out the nail.B Q needs less effort than P to pull out the nail.C The distance of the nail from the fulcrum does not influence the effort used.D If the distance of effort is nearer to the fulcrum, the effort used will decreased.

PMR 2007

Diagram 15

5 Diagram 4 shows the process of pruning leaves.

Diagram 4

The tool used can be classified as a first class lever because

A The load is between the fulcrum and the forceB The fulcrum is between the load and the force C The force is between the load and the fulcrumD The load is the same position as the fulcrum

PMR 2006

6 Diagram 20 shows a vegetable seller carrying two baskets, F and G. F has a mass of 40 kg and G has a mass of 60 kg. The distance between G and the seller is 1.0 m.

Diagram 20

What should be the distance between the seller and F in order to balance both the baskets?

A 0.5mB 1.0mC 1.5mD 2.5m

PMR 2006

6 The diagram shows a balanced lever system.

What is the load of X?

A 10NB 20NC 40ND 80N

PMR 2005

7 The diagram shows a lever system. The distance between each of the point on the lever is the same. At which A, B ,C or D should the fulcrum be, so that the lever is balanced?

PMR 2004

1 Figure 1 shows a wheelbarrow. (PMR 2005)

Figure 1.1

(a) On Figure 1.1, label the position of the fulcrum.(1 mark)

(b) (i) Based on Diagram 1.1, state the class of lever of the wheelbarrow.

______________________________________________________________(1 mark)

(ii) Give one reason for your answer in (b)(i).

____________________________________________________________ (1 mark)

(c) Based on Figure 1.2, choose one tool with the same class of lever as the wheelbarrow in Figure 1.1.

Mark ( ) in the box for the tool.

Fishing rod Nutcracker Pliers

Figure 1.2(1 mark)

(d) Figure 1.3 shows the situation when a force and a load are balanced.

2

Figure1.3

Calculate force P needed to balance the metre rule.

Use the following formula:

Load x Distance of load from fulcrum = Force x Distance of force from the fulcrum

(2 marks)

Diagram 2.1 shows a pair of pliers. (PMR 2007)

Diagram 2.1

(a) (i) What is the class of lever of the pair of pliers?

_____________________________________________________________(1 mark)

(ii) State one reason for the answer in 2(a) (i).

_____________________________________________________________(1 mark)

(b) Based on Diagram 2.1, why is it easier to cut the wire when we hold the pliers at K rather than at L?

_______________________________________________________________ _______________________________________________________________

(1 mark)

(c) Diagram 2.2 shows a worker carrying a load using a wheel barrow.

Diagram 2.2

Draw a lever system for the wheel barrow and label the position of load, force and fulcrum.

( 2 marks)

(d) Diagram 2.3 shows a system when a force and a load are balanced.

3

Force 50 N Load W

20 cm

Diagram 2.3

Calculate load W when the system is in equilibrium. Use the following formula :

W = _________________ N(2 marks)

(e) Diagram 2.4 shows two persons, P and Q, rowing their boats.

Figure 2.4

Why does P use less force than Q to row his boat?

_______________________________________________________________

_______________________________________________________________(1 mark)

(a) Diagram 3.1 shows four devices, P, Q, R and S that use the principle of lever. (PMR 2008)

Load x Distance of load from the = Force x Distance of force from the fulcrum fulcrum

Metre rule

80 cm

Diagram 3.1

State one characteristic that can be observed from any three devices by referring to the positions of fulcrum, load and force.

Device Characteristic

(3 marks)

(b) Classify the devices, P, Q, R and S into two groups based on their common characteristics.

Common characteristics

Devices

(4 marks)

(c) Diagram 3.2 shows three situations, J, K and L, of a device using principle of lever.

P, Q, R, S

Diagram 3.2Based on Diagram 3.2

(i) State one inference about the device.

____________________________________________________________(1 mark)

(ii) Predict the force needed to lift the rock at L.

____________________________________________________________(1 mark)

(iii) State the relationship between the length of the crow-bar and the force needed to lift the rock.

____________________________________________________________(1 mark)

SIMPLE MACHINES

ANSWER:

1. A2. C3. D4. B5. B6. C7. B

1(a)

(b)

(c)

(d)

(i) Second class lever(ii) Load is between fulcrum and effort.

Nutcracker

40 x 20 = 100 x P 800 = 100P 8N = P

PMR 20072(a)

(b)

(c)

(d)

(e)

(i) First class lever(ii) The fulcrum is between the effort and load / The fulcrum is in the middle

The longer the distance of the effort from the fulcrum, the less effort is required.

Force / E

L / Load F / Fulcrum

W x 100 = 50 x 20 W = 10 N

Distance of the applied force from the fulcrum is longer. / Distance of the load from the fulcrum is shorter.

PMR 20083(a) Able to state one characteristic of any three devices.

P : Load is between effort and fulcrum.

fulcrum

(b)

(c)

Q : Effort is between load and fulcrum.R : Fulcrum is between effort and load.S : Fulcrum is between effort and load.

Common characteristics

Devices

(i) The length of the crow bar influences the force needed to lift the rock.(ii) 100 N(iii) The longer the length of the crow bar, the less force needed to lift the rock.

P, Q, R, S

The fulcrum is between the load and effort

The fulcrum is not between the load and effort

PliersScissors

Bottle openerIce tongs