- 3 A A Lamp Unit In A Lighthouse Similar To That In Figure 2 Rotates At 12 Rpm Given That The Instantaneous Tangential 1 (160.09 KiB) Viewed 32 times
3. a. A lamp unit in a lighthouse similar to that in Figure 2 rotates at 12 rpm given that the instantaneous tangential velocity of the lamp is 0.9 m/s calculate the diameter of the lamp. [8 marks] b. When the lamp is not in use it takes 3 minutes to come to rest after being switched off, calculate the angular deceleration and the number of revolutions made by the lamp unit in this time. [9 marks] Given that when the lamp is switched on it takes a torque of 250Nm to get the lamp up to its maximum speed of 10 rpm in 25 seconds, caleulatę: c. The power needed to get the lamp up to this speed, [3 marks] d. The inertia of the lamp, [8 marks] e. The mass of the lamp, [6 marks] f. The kinetic energy of the lamp at this speed. [3 marks] Figure 2: Light house and Lamp unit.