1. P3 Pendulum and Hydraulics

2. Lesson Objective Key: Calculate the pendulum speed Stretch: Identify the key words in an exam question and then answer it.

3. Centre of Mass The centre of mass of an object is that point at which the mass of the object may be thought to be concentrated. b) If freely suspended, an object will come to rest with its centre of mass directly below the point of suspension. c) The centre of mass of a symmetrical object is along the axis of symmetry. d) For a simple pendulum: T = 1/f T = time in seconds, f = speed in hertz e) The time period depends on the length of a pendulum

4. Hydraulics Hydraulics is basically using pressurized liquids, you probably think of them with engineering.

5. Hydraulics a) Liquids are virtually incompressible, and the pressure in a liquid is transmitted equally in all directions. b) The use of different cross-sectional areas on the effort and load side of a hydraulic system enables the system to be used as a force multiplier. c) The pressure in different parts of a hydraulic system is given by: P = F/A P = Pressure in Pascals (Pa), F = Force in Newtons (N), A = cross sectional area measured in Metre squared

6. The diagram shows a simple hydraulic jack. The jack is designed to lift a large weight using a much smaller force. 8 (a) Complete the following sentence. A hydraulic jack is an example of a...................................................... multiplier. (1 mark) 8 (b) Calculate the pressure, in N/cm 2, created on the small piston by the force of 50 N pushing downwards. Write down the equation you use, and then show clearly how you work out your answer............................................................................................................................................. Pressure =................................................. N/cm 2 (2 marks) 8 (c) Complete the following sentence. The pressure at Y will be...................................................................... the pressure at X. (1 mark)