Some materials sag under their own weight, or try to return to their original form, when subjected to heat. This could be a big problem for the automobiles that use plastic components like quarter panels...they might sag when parked in blacktop parking lots on a hot, sunny days! Because of the cold day we did not have time to do this test during Science Club. The plastics and the linoleum were held under a 150 watt light bulb for 75 minutes. Three materials sagged; solid vinyl tile (nine percent), linoleum (seven percent), and acrylic (one percent).