.internal-energy3{width:128px; height:42px ;}
.internal-energy4{width:155px; height:99px ;}
.internal-energy-problem{width:166px; height:111px ;}
.internal-energy2{width:140px; height:267px ;}
.internal-energy-problem3{width:32px; height:82px ;}
.internal-energy-problem2{width:196px; height:202px ;}
.internal-energy-problem4{width:203px; height:64px ;}
.internal-energy-problem5{width:199px; height:161px ;}