The 80kg student balances a 1300kg elephant on a hydraulic lift. (U-Tube)

What is the diameter of the piston the student is standing on?
When a second student joins the first, the height difference between the liquid levels in the right and left pistons is 40cm . What is the second student's mass?

Its 900kg/m^3 for the density of liquid I think.

I do not know. All I know is the ratio of areas.

80 (pi r^2) = 1300 (pi R^2)

By the way to do the second one you must know the density of the fluid.

These are very strange questions. Are you sure you have copied them correctly?

To find the diameter of the piston the student is standing on, we can use the concept of Pascal's Law, which states that when pressure is applied to a fluid in a confined space, the pressure is transmitted equally in all directions.

Let's first determine the pressure exerted by the student on the hydraulic lift. We know that the student's weight is 80 kg, and we can use the acceleration due to gravity (9.8 m/s^2) to calculate the force exerted by the student.

Force = mass x acceleration
Force = 80 kg x 9.8 m/s^2
Force = 784 N

Since the pressure is transmitted equally, we can equate the pressure exerted by the student to the pressure exerted by the elephant.

Pressure_student = Pressure_elephant

The pressure exerted by an object can be calculated using the formula:

Pressure = Force / Area

We can rearrange the formula to solve for the area:

Area = Force / Pressure

We have the force exerted by the student (784 N), and we know that the elephant's weight is 1300 kg. We can use the same procedure to calculate the force exerted by the elephant.

Force_elephant = mass x acceleration
Force_elephant = 1300 kg x 9.8 m/s^2
Force_elephant = 12740 N

Now, let's calculate the area of the piston the student is standing on:

Area_student = Force_student / Pressure_student
Area_student = 784 N / Pressure_student

Similarly, let's calculate the area of the piston supporting the elephant:

Area_elephant = Force_elephant / Pressure_elephant
Area_elephant = 12740 N / Pressure_elephant

Since the pressure is transmitted equally, we can equate the areas:

Area_student = Area_elephant

Now we can solve for the diameter of the piston using the formula for the area of a circle:

Area = π * (diameter/2)^2

By rearranging the formula, we get:

Diameter = √(4 * Area / π)

Now we can substitute the known values and calculate the diameter of the piston the student is standing on.