The airplane was substantially damaged during an instructional flight when it impacted power lines and terrain after takeoff from runway 9 (4,508 feet by 75 feet, asphalt). The flight instructor reported that the accident takeoff began from a taxiway intersection, with approximately 4,000 feet of runway available. He stated that the dual student was slow in applying the throttle and estimated that an additional 200 - 500 feet of runway was used before full throttle was reached. After liftoff, he noted that the airplane was not climbing as expected. He stated that the engine tachometer indicated only 2,000 revolutions per minute (RPM), instead of the normal 2,500 RPM. The flight instructor reported that at that point there was no longer sufficient runway remaining to land, so he elected to continue the flight. He stated that the main landing gear struck power lines off the end of the runway, and the airplane subsequently impacted a field on the opposite side of the lines. The nose landing gear collapsed and the airplane came to rest. Published performance data for the accident airplane indicated that the takeoff ground roll required was approximately 850 feet. The distance required to takeoff and clear a 50-foot obstacle was about 1,585 feet. The distance required to land over a 50-foot obstacle was approximately 1,090 feet. The elevation of the departure airport was 481 feet.