Measurements of microtremors, slope of the land, and motion of tectonic plates predict earthquakes. But we can't predict WHEN accurately enough yet to make the prediction useful to the general public.
Newton's second law states that the force applied to an object is equal to the product between the mass m of the object and its acceleration a:

Using

and

, we can find the value of the force applied to the roller-blade to obtain this acceleration:
Answer:
a) 24.692 m/s
b) 19.4 m
Explanation:
To calculate the velocity at the nozzle outflow (V2) we use the Bernoulli equation:

We know that the velocity above the oil surface (V1) and the pressure at the nozzle outflow (P2) are negligible, the height in the exit is zero (Z2) then:

a) The velocity (V2) is:


![V2=[(\frac{P1}{pg}+Z1)(2g)]^{1/2}](https://tex.z-dn.net/?f=V2%3D%5B%28%5Cfrac%7BP1%7D%7Bpg%7D%2BZ1%29%282g%29%5D%5E%7B1%2F2%7D)
Substituting the known values we can get the velocity at the out:
Atmospheric pressure= 101000 Pa
Oil density= 0.88x(Water density)=0.88(1000kg/m3)=880kg/m3
![V2=[(\frac{150000Pa+101000 Pa}{(880 kg/m3)(9.81m/s)}+2m)(2(9.81m/s2))]^{1/2}](https://tex.z-dn.net/?f=V2%3D%5B%28%5Cfrac%7B150000Pa%2B101000%20Pa%7D%7B%28880%20kg%2Fm3%29%289.81m%2Fs%29%7D%2B2m%29%282%289.81m%2Fs2%29%29%5D%5E%7B1%2F2%7D)

b) To calculate the height we have to apply the Bernoulli equation between the outflow and the maximum height (Z3), so:

We know that the velocity above the stream (V3) and the pressure at the nozzle outflow (P2) are negligible, the pressure at the top of the stream (P3) is the atmospheric pressure, then:


Substituting the known values, the height (Z3) is:

Z3=Maximum Height=19.376=19.4 m