# 5. Centripetal forces (Radial outward) and plate movements

Consideration of the calculations in Appendix 4 shows that the Centripetal or Radial Outward Force F= Mω2R (in Newtons) is responsible for the equatorial bulge that causes a 0.34% reduction in the gravitational force from that experienced at the poles where the rotational velocity is zero. This difference is considered enough to cause the plates to move around the Earth on a frictionless surface.

At this junction it is pertinent to note that due to the low rotational velocity of Venus at the equator (one rotation in 243 Earth days = 6.5 kmh-1) compared with 1674.5 kmh-1 on Earth, the centripetal forces available compared to the similar-sized planet Earth will be in the ratio of (6.5)2 / (1674.5)2 = 42.25/2,803,950.25 = 0.000015:1. This would give a stress value of 3.9x10-3 Nmm-2 (0.059 psig). The circumferential forces thus available for tectonic activity on Venus are extremely small.

# ⇨

Fig 22

The calculations derived in Appendix 4 are mainly applicable to the longitudinal East and West movements of the plates away from the African Plate and at first sight do not really help explain the northwards movement and breakup of Pangea from the Permian to the present. A demonstration rig (Fig 22) was made using a hemispherical bowl with 4 vertical slots in which different sized metal bolts are free to move along and within the slots.

On rotating the bowl, the bolts travelled vertically upwards and outwards. This centripetal force action mimicked the northwards movement of Pangea and the associated upwards separation of the South American plate as it went westwards and the Indian and Australian plates as they moved eastwards. The possibility that the above process is responsible for the creation of the divergent southern circumferential East Pacific and Antarctic ridges and the south-west and south-east Indian ridge boundaries is a matter for consideration. Furthermore, it is also feasible that the same centripetal forces are simultaneously pushing the Antarctic plate southwards to move into a larger area around the south pole The outward centripetal forces creating the oblate shape of the Earth will also tend to move or pivot the northern land masses comprising the Eurasian and North American plates in a southerly direction into a larger diameter area. These processes will result in putting the Pacific Basin under compression.

Fig 23 displays the National Geographic37A Mid-Ocean east Pacific and Antarctic ridges including the south-west and east Indian ridge boundaries with perpendicular fracture zones.

The pictorial ‘force’ diagram shown in Fig 24 yields a viable explanation how west-east centripetal or radial forces can result in the south-north plate separation.

Fig 23

Fig 24