On July 23, 1998, about 1030 Eastern Daylight Time, a Piper PA-28-140, N7406J, was substantially damaged during landing at Nantucket Memorial Airport (ACK), Nantucket, Massachusetts. The student pilot received minor injuries. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed for the personal flight, conducted under 14 CFR Part 91. The student pilot stated that she thought she received conflicting instructions from the tower. She said she was first told to set up a right base for Runway 24. She was thinking it should have been a left base when the tower controller asked her what she was doing. When she responded that she was setting up for a right base to Runway 24, the tower controller told her it was supposed to be a right base for Runway 30. The pilot then departed the traffic pattern, and reentered a pattern for Runway 30. She felt rattled by the confusion, and found herself over Runway 30 at 300 feet and "too fast." She thought about going around, but heard the tower comment to Runway 24 traffic. She felt that if she did do a go-around, she might conflict with that traffic. She pulled back on the throttle to make the landing, and the airplane hit hard. It bounced into the air again, touched down, and skidded off the runway to the left. A review of the air traffic control voice communications tape revealed that both Runway 24 and Runway 30 were being used. The tower controller instructed the student pilot to "circumnavigate the island to east side, enter a 2 mile right base for Runway 30." The student pilot acknowledged the instructions. Winds recorded about 35 minutes prior to the accident were from 190 degrees magnetic at 6 knots, and winds recorded about 25 minutes after the accident were from 200 degrees magnetic at 9 knots.