"Can anyone tell me if i can play a VHS tape recorded in Australia, in an American machine ?"
Only if the Australian recording was done in NTSC. Otherwise, no.
An elaboration:
Australia uses the PAL system for video while North America uses the NTSC system. Linear tape speeds and head drum speeds are completely different for NTSC and PAL variations of the VHS format.
For instance, the head drum rotation speed is 1800 RPM for NTSC VHS while it is 1500 for PAL VHS. This is because the head rotation directly coincides with the scan rate of the display.
One complete revolution of the head drum equals one frame of video (a half rotation equals half the interlace field), so the head drum must rotate 30 times in one second for 30 frames of video in NTSC. For PAL, the head drum must rotate 25 times in one second for 25 frames of video in PAL. Multiply the number of times the head must rotate per second to 60 (which is how many seconds are in a minute) to obtain the head drum RPM.
Linear tape speeds for normal and slow speeds are also different. An NTSC T-120 cassette is equivalent to a PAL E-180 cassette. Both are the same length but, due to the slower head drum RPM in PAL VHS, the tape speed doesn't have to be as fast for standard play to avoid crosstalk problems. - Reinhart