A car moving at a speed of 36 km/hr is taking a turn on a circular road of radius 50 m. A small wooden plate is kept on the seat with its plane perpendicular to the radius of the circular road (figure 7-E4). A small block of mass loo g is kept on the seat which rests against the plate. The friction coefficient between the block and the plate is μ = 058. (a) Find the normal contact force exerted by the plate on the block. (b) The plate is slowly turned so that the angle between the normal to the plate and the radius of the road slowly increases. Find the angle at which the block will just start sliding on the plate.



The speed in MKS will be, v=10m/s


The normal force will be balancing the centrifugal force. So,






(b) 30o



Here Fcsinθ will try to move the block while Fccosθ will provide the normal reaction force. As soon as Fcsinθ exceeds the value of friction force, the block will move. So,







Hence as soon as the angle exceeds ∏/6 the block will start moving.


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