Intensity Problem set

Question 1
A droplet of water in a pond converts 1 J of potential energy to kinetic energy in half a second. A duck 50 cm away experiences this. What intensity of the wave does the duck experience? How far would the duck have to move from the source to ensure that the sound intensity dropped to 1 Wm-2?

Question 2
A speaker emits a note with a power of 36 W. What is the Sound Intensity 3 m away? What would be the sound intensity at half this distance?

Question 3
An explosion released 15000 J of heat and kinetic energy in 0.05 s. What is the intensity of the explosion experienced by someone standing 6m away? What intensity would be experienced by someone a distance of 12m away?

Question 4
A star explodes releasing gamma radiation, which emits 64.5 GJ of energy in 0.0003 s. What is the intensity of gamma ray radiation striking a planet 50,000,000 km away? What would the light intensity be at a further 20,000,000 km?

Question 5
A light bulb of power 60 W is turned on in a room. What is the intensity of the light shining on a wall 1.5 m away?


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