MACHINES
2015
1. i) Give the expression for mechanical advantage of an inclined plane in terms of the length of an inclined plane.
ii) Name a common device where a gear train is used. [2]
2. Draw a simplified diagram of a lemon crusher, indicating direction of load and effort. [2]
3. A block and tackle system has VR = 5.
i) Draw a neat labeled diagram of a system indicating the direction of its load and effort.
ii) Rohan exerts a pull of 150 kgf. What is the maximum load he can raise whith this pulley if its efficiency is 75%? [4]
2014
2. Draw a diagram to show how a single pulley can be used so as to have its ideal MA = 2. [3]
3. Derive a relationship between mechanical advantage, velocity ratio and efficiency of a machine. [3]
4. For a given height h, _________ the length l of the inclined plane, lesser will be the effort required. [2]
2013
1. A type of single pulley is very often used as a machine even though it does not give any gain in mechanical advantage. I) Name
the type of pulley used. Ii) For what purpose is such a pulley used? [2]
2. i) In what way does an ‘ideal machine’ differ from a ‘Practical machine’? ii) Can a simple machine act as a force multiplier and
a speed multiplier at the same time? [2]
3. Which class of lever found in the human body is being used by a boy – i) when he holds a load on the palm of his hand. Ii) when
he raises the weight of his body on his toes? [2]
4. A coolie is pushing a box weighing 1500 N up an inclined plane 7.5 m long on to a platform, 2.5 m above the ground. I)
Calculate the mechanical advantage of the inclined plane. Ii) Calculate the effort applied by the coolie. Iii) In actual practice, the
coolie needs to apply more effort than what is calculated. Give one reason why you think the coolie needs to apply more effort.
[3]
5. A block and tackle system of pulleys has a velocity ratio 4. I) Draw a labelled diagram of the system indicating clearly the points
of application and directions of load and effort. Ii) What is the value of the mechanical advantage of the given pulley system if it
is an ideal pulley system? [4]
2012
1. A body of mass 30 kg is sitting at a distance of 2 m from the middle of a see-saw. Where should a boy of mass 40 kg sit so as to
balance the see-saw? [2]
2. i) What is meant by the term ‘moment of a force’?
ii) If the moment of force is assigned a negative sign then will the turning tendency of the force be clockwise or anti-clockwise?
[2]
3. State the class of levers and the relative positions of load L, effort E and fulcrum F in each of the following cases – a bottle
opener, sugar tongs.
ii) Why is less effort needed to lift a load over an inclined plane as compared to lifting the load directly? [3]
4. i) A moving body weighing 400N possesses 500J of kinetic energy. Calculate the velocity with which the body is moving. (g =
10m/s2)
ii) Under what condition will a set of gears produce – i) a gain in speed ii) a gain in torque. [4]
2011
1. Name a machine which can be used to i) multiply force ii) change the
direction of the force applied. [2]
2. The diagram shows a lever in use.
i) To which class of lever does it belong?
ii) If FA = 40 cm, AB = 60 cm, then find the mechanical advantage of the
lever. [2]
3. i) What is meant by an ideal machine?
ii) Write a relationship between the mechanical advantage and velocity
ratio of an ideal machine.
iii) A coolie carrying a load on his head and moving on a frictionless horizontal platform does no work. Explain the reasons why.
[3]
2010
1. i) Why is the mechanical advantage of a lever of the second order always greater than one?
ii) Name the type of single pulley that has a mechanical advantage greater than one. [2]
2. i) Write a relation expressing the mechanical advantage of a lever.
ii) Write an expression for the mechanical advantage of an inclined plane.
iii) Give two reasons as to why the efficiency of a single movable pulley system is always less than 100% [4]
2009
1. (i) With reference to the terms mechanical advantage, velocity ratio and efficiency of a machine, name the term that will not
change for a machine of a given design.
(ii) Define the term stated by you in part (i). [2]
2. A pulley system comprises two pulleys, one fixed and the other movable.
(i) Draw a labelled diagram of the arrangement and show clearly the directions of all the forces acting on it.
(ii) What change can be made in the movable pulley of this system to increase the mechanical advantage of the system? [3]
2008
1. Copy the diagram of the forearm given alongside; indicate the positions of Load, Effort and
Fulcrum. [2]
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