Advanced physics

Calcualte the mass that must be hung from the balance arm at 90cm.

A circular opening in the sloping side of a reservoir is closed by a disc valve of 70 cm diameter, as shown in Figure 1.2. The disc is hinged and the balance arm weight is just sufficient to hold the valve closed when the reservoir is empty. An additional weight is hung from the balance arm 90 cm from the hinge so that the valve remains closed until the water level is 60 cm above the centre of the valve. reservoir 60 90 cm 60 cm 7 cm M 70 cmUseful information: Density of water, p = 1000 kg m-3 TR4 Second moment of inertia for a circle, = 4 Point at which the pressure acts, yp = yc + Ayc