In: Physics
A bucket of water is sliding down a frictionless ramp, whose angle of inclination is \thetaθ. What angle does the water surface make with the horizontal? Is it zero, \thetaθ, or greater than \thetaθ? You must provide a convincing argument.
In the diagram it can be easily seen that there are only one
single force working on the water inside the bucket Mg (M = mass of
water) (the normal reaction(N) between bucket sides and water will
cancel each other). So when we see the component of Mg , one is Mg
Sin(theta) which is working in the direction of ramp and one is Mg
Cos(theta) which is perpendicular to ramp.We can easily say that
water will move to the direction in which forces are working on
it.It can't move parallel to ramp
as the normal reaction from bucket's lower part will cancel out the
Mg cos(theta) but the force Mg Sin (theta) will drive it in the
direction of ramp.
As there is no mention of Surface tension of water so it will be purely in the direction of ramp. Hence water surface will make an angle Theta with horizontal.
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